mirror of https://github.com/tLDP/LDP
updated
This commit is contained in:
gferg
parent
62f6e6a995
commit
36ecdef705
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@ -6,6 +6,127 @@
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http://personal.riverusers.com/~thegrendel/Change.log
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------------------------------------------------------------------------
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Version 2.2 'CRANBERRY' release, 11/01/03
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Comments: Major release.
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Much new material added.
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1) In "Text Processing Commands" of "External Commands and Filters" chapter:
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Fixed up listing of "gettext."
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(Thanks, Bruno Haible.)
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Added "msgfmt."
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Renamed "du.sh" example to "Du.sh" to avoid confusion with system 'du"
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command.
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(Thank you, Bill Gradwohl.)
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2) In "Typing Variables" section of "Variables Revisited" chapter:
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At 'declare,' added example of arithmetic operations enabled
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with '-i' option.
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Fixed term heading to "-x var=$value." (Thank you, Bill Gradwohl.)
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3) Modified "Localization" appendix, per suggestions by Bruno Haible.
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4) In "Internal Variables" section of "Variables Revisited" chapter:
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Added '$PROMPT_COMMAND.'
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Fixed an error in "arglist.sh" example.
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Added Bjön Eriksson's "readpipe.sh" example.
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5) In "Local Variables" section of "Functions" chapter:
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Modified note in example script in footnote 2.
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(Thanks, Zhao You Bing.)
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6) Fixed up references to my own "yawl" package, to reflect
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the latest update.
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7) In "Writing Scripts" section of "Exercises" appendix:
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In "Difficult" section, added "Testing Passwords" exercise .
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8) In "Subshells" chapter:
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In in-line script example that tests whether variable is set,
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noted that this also tests whether that variable is present
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in the environment (exported).
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(Thank you, Mr. Fred.)
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9) In "Comparison Operations" section of "Tests" chapter:
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Corrected typos in "str-test.sh" example.
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(Thank you, Bill Gradwohl.)
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10) In "Internal Commands" chapter:
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Fixed a typo in "ex46.sh" example.
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(Thank you, Bill Gradwohl.)
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Fixed a typo in "ex33.sh" example,
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and implemented changes to explain what OPTIND does.
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(Thank you, Bill Gradwohl.)
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11) In "Information and Statistics" subsection of "System and
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Administrative Commands" chapter:
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Substituted better example of 'sar' output.
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(Thank you, Sebastien Godard.)
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12) In "Local Variables " section of "Functions" chapter:
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Fixed up "ex62.sh" example.
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(Thank you, Bill Gradwohl.)
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13) In "Basic Commands" section of "External Commands" Chapter:
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Added to discussion of 'ln.'
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Fixed typo in in-line example listing at 'cat,tac.'
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(Thank you, Bill Gradwohl.)
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14) In "Miscellaneous Commands" section of "External Commands" Chapter:
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Corrected "ex33a.sh" example.
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Noted that 'getopt' permits long options.
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(Thank you, Eric Levy.)
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15) In "RANDOM" section of "Variables Revisited" chapter:
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Noted exception in "Jipe" method of generating random numbers
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within a given range.
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Added improved formula for generating randoms within a range.
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(Thank you, Bill Gradwohl.)
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Added "random-between.sh" example for generating randoms within a range.
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(Thank you, Bill Gradwohl.)
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16) In "Arrays" chapter:
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Changed in-line example of miscellaneous array operations
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to an external shell script and enhanced it, per suggestions
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by Michael Zick.
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Added "array-strops.sh" example of using string manipulation operations
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on arrays.
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Added "array-assign.bash" script.
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Added "array-append.bash" script.
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(Thank you, Michael Zick.)
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17) In "Special Characters" chapter:
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At "Control Characters," section, added Ctl-B, Ctl-I, Ctl-S, and
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Ctl-K listings.
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Fixed listing for Ctl-M (Thanks, Lee Maschmeyer.)
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Also added Lee Maschmeyer's in-line example.
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18) In "Gotchas" chapter:
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At "Piping echo output . . . " inserted missing space.
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19) In "Exit and Exit Status" chapter:
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Added material to discussion of "bare" exit.
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20) Added "Where to Go For Help" section
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to "Endnotes" chapter.
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21) In the "Sed and Awk Micro-primer" appendix:
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Added "nyal's" "letter-count.sh" script.
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22) In "Contributed Scripts" appendix:
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Added Michael Zick's "protect_literal.sh" script.
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Added Michael Zick's "unprotect_literal.sh" script.
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Added Michael Zick's "basics-reviewed.bash" script.
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23) In "Bibliography" section:
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Added 'Bash Navigator' listing.
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Added 'GNU Bash Reference Manual' listing (thanks, Brian Gough).
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24) Miscellaneous cleanups on example scripts.
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Version 2.1
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'HUCKLEBERRY' release, 09/14/03
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@ -17,7 +138,7 @@ Version 2.1
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Added "Miscellaneous Construct" table.
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Added variable prefix matching to "Parameter Substitution" table.
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3) In "Internal Variables" chapter"
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3) In "Internal Variables" section of "Variables Revisited" chapter:
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Noted that "$*" must be quoted to differentiate it from "$@" variable,
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and added a case to "arglist.sh" example to demonstrate this.
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(Thanks, Heiner Steven.)
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@ -139,7 +260,11 @@ bumped up to a major version. This is now officially a "mature" project.
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"Quoting" chapter
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"advisable in enclose it" --> "advisable to enclose it"
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17) Corrected several minor typos in the text and script examples.
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17) In "Copyright" chapter:
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Added note about contributors rights.
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Added mention of Russian translation being underway.
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18) Corrected several minor typos in the text and script examples.
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@ -1040,8 +1165,8 @@ Version 1.0 (stable!), released 10/14/01
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o Moved "Shell Wrappers" section from "Starting Off With a Sha-Bang"
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chapter to "Miscellany" chapter.
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6) In "Local Variables and Recursion" section of "Functions" chapter, defined
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"recursion" in more detail.
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6) In "Local Variables and Recursion" section of "Functions" chapter:
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Defined "recursion" in more detail.
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7) Modified in-line example in "Special Variable Types" section of
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"Introduction to Variables and Parameters". Thanks, John Villalovos for
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@ -1,9 +1,9 @@
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SOME SCRIPTS WILL NOT RUN
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SOME SCRIPTS WILL NOT RUN AS IS
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Note that the source code for a few of the example shell scripts,
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Note that the source code for some of the example shell scripts,
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du.sh
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Du.sh
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encryptedpw.sh
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ex57.sh
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ex70.sh
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@ -12,11 +12,13 @@ ex71a.sh
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ex71b.sh
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logevents.sh
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m4.sh
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pb.sh
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pw.sh
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read-r.sh
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rnd.sh
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rot13.sh
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here-function.sh
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array-assign.bash
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directory-info.sh (lines 273 and 353)
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bashrc (comments on lines 596 and 618)
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@ -182,7 +182,7 @@ Uncomment line below to generate index.
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<!ENTITY pattmatching SYSTEM "patt-matching.sh">
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<!ENTITY isalpha SYSTEM "isalpha.sh">
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<!ENTITY rnd SYSTEM "rnd.sh">
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<!ENTITY du SYSTEM "du.sh">
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<!ENTITY du SYSTEM "Du.sh">
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<!ENTITY refparams SYSTEM "ref-params.sh">
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<!ENTITY primes SYSTEM "primes.sh">
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<!ENTITY vartrace SYSTEM "vartrace.sh">
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@ -273,6 +273,16 @@ Uncomment line below to generate index.
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<!ENTITY embarr SYSTEM "embedded-arrays.sh">
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<!ENTITY generatescript SYSTEM "generate-script.sh">
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<!ENTITY scriptarray SYSTEM "script-array.sh">
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<!ENTITY randombetween SYSTEM "random-between.sh">
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<!ENTITY arrayops SYSTEM "array-ops.sh">
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<!ENTITY arraystrops SYSTEM "array-strops.sh">
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<!ENTITY arrayappend SYSTEM "array-append.bash">
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<!ENTITY arrayassign SYSTEM "array-assign.bash">
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<!ENTITY lettercount SYSTEM "letter-count.sh">
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<!ENTITY protectliteral SYSTEM "protect_literal.sh">
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<!ENTITY unprotectliteral SYSTEM "unprotect_literal.sh">
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<!ENTITY basicsreviewed SYSTEM "basics-reviewed.bash">
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<!ENTITY readpipe SYSTEM "readpipe.sh">
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<!ENTITY usrmnt SYSTEM "usrmnt.sh">
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<!ENTITY dialog SYSTEM "dialog.sh">
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<!ENTITY evalex SYSTEM "eval.example">
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@ -296,8 +306,8 @@ Uncomment line below to generate index.
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</affiliation>
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</author>
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<releaseinfo>2.1</releaseinfo>
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<pubdate>14 September 2003</pubdate>
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<releaseinfo>2.2</releaseinfo>
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<pubdate>31 October 2003</pubdate>
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<revhistory>
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@ -431,6 +441,13 @@ Uncomment line below to generate index.
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<revremark>'HUCKLEBERRY' release: bugfixes and more material.</revremark>
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</revision>
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<revision>
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<revnumber>2.2</revnumber>
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<date>31 October 2003</date>
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<authorinitials>mc</authorinitials>
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<revremark>'CRANBERRY' release: Major update.</revremark>
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</revision>
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</revhistory>
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@ -454,7 +471,7 @@ Uncomment line below to generate index.
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linkend="bzipref">bzip2-ed</link> <quote>tarball</quote>
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including both the SGML source and
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rendered HTML, may be downloaded from <ulink
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url="http://personal.riverusers.com/~thegrendel/abs-guide-2.1.tar.bz2">
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url="http://personal.riverusers.com/~thegrendel/abs-guide-2.2.tar.bz2">
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the author's home site</ulink>. See the <ulink
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url="http://personal.riverusers.com/~thegrendel/Change.log">change
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log</ulink> for a revision history.</para>
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@ -2676,6 +2693,11 @@ echo $a # 28</programlisting></para>
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<itemizedlist id="ctlchar">
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<listitem>
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<para><userinput>Ctl-B</userinput></para>
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<para>Backspace (nondestructive).</para>
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</listitem>
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<listitem>
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<para><userinput>Ctl-C</userinput></para>
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<para>Terminate a foreground job.</para>
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@ -2697,7 +2719,7 @@ echo $a # 28</programlisting></para>
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<listitem>
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<para><userinput>Ctl-H</userinput></para>
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<para>Backspace.</para>
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<para><quote>Rubout</quote> (destructive backspace).</para>
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<para>
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<programlisting>#!/bin/bash
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# Embedding Ctl-H in a string.
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@ -2713,9 +2735,19 @@ echo; echo</programlisting>
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</para>
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</listitem>
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<listitem>
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<para><userinput>Ctl-I</userinput></para>
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<para>Horizontal tab.</para>
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</listitem>
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<listitem>
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<para><userinput>Ctl-J</userinput></para>
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<para>Carriage return.</para>
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<para>Newline (line feed).</para>
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</listitem>
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<listitem>
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<para><userinput>Ctl-K</userinput></para>
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<para>Vertical tab.</para>
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</listitem>
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<listitem>
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@ -2727,10 +2759,33 @@ echo; echo</programlisting>
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<listitem>
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<para><userinput>Ctl-M</userinput></para>
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<para>Newline.</para>
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<para>Carriage return.</para>
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<para>
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<programlisting>#!/bin/bash
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# Thank you, Lee Maschmeyer, for this example.
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read -n 1 -s -p $'Control-M leaves cursor at beginning of this line. Press Enter. \x0d'
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# Of course, '0d' is the hex equivalent of Control-M.
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echo >&2 # The '-s' makes anything typed silent,
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#+ so it is necessary to go to new line explicitly.
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read -n 1 -s -p $'Control-J leaves cursor on next line. \x0a'
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echo >&2 # Control-J is linefeed.
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read -n 1 -s -p $'And Control-K\x0bgoes straight down.'
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echo >&2 # Control-K is vertical tab.
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exit 0</programlisting>
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</para>
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</listitem>
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<listitem>
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<para><userinput>Ctl-S</userinput></para>
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<para>Suspend (XOFF).</para>
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<para>This freezes <filename>stdin</filename> in a terminal.</para>
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</listitem>
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<listitem>
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<para><userinput>Ctl-U</userinput></para>
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<para>Erase a line of input.</para>
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</listitem>
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|
@ -3751,10 +3806,49 @@ bar' # Escape character \ taken literally because of strong quoting.
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must be a decimal number in the <returnvalue>0</returnvalue> -
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<returnvalue>255</returnvalue> range).</para>
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|
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<note><para>When a script ends with an <command>exit</command> that has
|
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<note>
|
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|
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<para>When a script ends with an <command>exit</command> that has
|
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no parameter, the exit status of the script is the exit status of
|
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the last command executed in the script (<emphasis>not</emphasis>
|
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counting the <command>exit</command>).</para></note>
|
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counting the <command>exit</command>).</para>
|
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|
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<para><programlisting>#!/bin/bash
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COMMAND_1
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. . .
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# Will exit with status of last command.
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COMMAND_LAST
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|
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exit</programlisting></para>
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|
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<para>The equivalent of a bare <command>exit</command> is
|
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<command>exit $?</command> or even just omitting the
|
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<command>exit</command>.</para>
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|
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<para><programlisting>#!/bin/bash
|
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|
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COMMAND_1
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. . .
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# Will exit with status of last command.
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COMMAND_LAST
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exit $?</programlisting></para>
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<para><programlisting>#!/bin/bash
|
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|
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COMMAND1
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|
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. . .
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|
||||
# Will exit with status of last command.
|
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COMMAND_LAST</programlisting></para>
|
||||
|
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</note>
|
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|
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<para><anchor id="exsref"></para>
|
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|
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|
|
@ -6047,6 +6141,22 @@ echo "Last command argument processed = $last_cmd_arg"
|
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</listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><varname>$PROMPT_COMMAND</varname></term>
|
||||
<indexterm>
|
||||
<primary>$PROMPT_COMMAND</primary>
|
||||
</indexterm>
|
||||
<indexterm>
|
||||
<primary>variable</primary>
|
||||
<secondary>prompt</secondary>
|
||||
</indexterm>
|
||||
<listitem>
|
||||
<para>A variable holding a command to be executed
|
||||
just before the primary prompt, <varname>$PS1</varname>
|
||||
is to be displayed.</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><anchor id="ps1ref"><varname>$PS1</varname></term>
|
||||
<indexterm>
|
||||
|
|
@ -7678,21 +7788,32 @@ echo "a = $a" # a = xyz23 xyz24
|
|||
|
||||
<varlistentry>
|
||||
<term><token>-i</token> <replaceable>integer</replaceable></term>
|
||||
|
||||
<listitem>
|
||||
|
||||
<para><programlisting>declare -i number
|
||||
# The script will treat subsequent occurrences of "number" as an integer.
|
||||
|
||||
number=3
|
||||
echo "number = $number" # number = 3
|
||||
echo "Number = $number" # Number = 3
|
||||
|
||||
number=three
|
||||
echo "number = $number" # number = 0
|
||||
# Tries to evaluate "three" as an integer.</programlisting>
|
||||
echo "Number = $number" # Number = 0
|
||||
# Tries to evaluate the string "three" as an integer.</programlisting></para>
|
||||
|
||||
Note that certain arithmetic operations are permitted
|
||||
<para>Certain arithmetic operations are permitted
|
||||
for declared integer variables without the need
|
||||
for <link linkend="exprref">expr</link> or <link
|
||||
linkend="letref">let</link>.</para></listitem>
|
||||
linkend="letref">let</link>.</para>
|
||||
|
||||
<para><programlisting>n=6/3
|
||||
echo "n = $n" # n = 6/3
|
||||
|
||||
declare -i n
|
||||
n=6/3
|
||||
echo "n = $n" # n = 2</programlisting></para>
|
||||
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
|
|
@ -7726,7 +7847,7 @@ echo "number = $number" # number = 0
|
|||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term>var=$value</term>
|
||||
<term>-x var=$value</term>
|
||||
<listitem>
|
||||
<para><programlisting>declare -x var3=373</programlisting></para>
|
||||
<para>The <command>declare</command> command permits
|
||||
|
|
@ -7810,14 +7931,11 @@ echo "number = $number" # number = 0
|
|||
</example>
|
||||
|
||||
|
||||
<note>
|
||||
|
||||
<para>
|
||||
<emphasis>Jipe</emphasis> points out another set of techniques
|
||||
for generating random numbers within a range.
|
||||
</para>
|
||||
<emphasis>Jipe</emphasis> points out a set of techniques for
|
||||
generating random numbers within a range.
|
||||
|
||||
<para>
|
||||
<programlisting># Generate random number between 6 and 30.
|
||||
rnumber=$((RANDOM%25+6))
|
||||
|
||||
|
|
@ -7825,10 +7943,27 @@ rnumber=$((RANDOM%25+6))
|
|||
#+ but the number must be evenly divisible by 3.
|
||||
rnumber=$(((RANDOM%30/3+1)*3))
|
||||
|
||||
# Note that this will not work all the time.
|
||||
# It fails if $RANDOM returns 0.
|
||||
|
||||
# Exercise: Try to figure out the pattern here.</programlisting>
|
||||
</para>
|
||||
|
||||
</note>
|
||||
|
||||
<para>
|
||||
<emphasis>Bill Gradwohl</emphasis> came up with an improved
|
||||
formula that works for positive numbers.
|
||||
<programlisting>rnumber=$(((RANDOM%(max-min+divisibleBy))/divisibleBy*divisibleBy+min))</programlisting>
|
||||
</para>
|
||||
|
||||
<para>Here Bill presents a versatile function that returns
|
||||
a random number between two specified values.</para>
|
||||
|
||||
<example id="randombetween">
|
||||
<title>Random between values</title>
|
||||
<programlisting>&randombetween;</programlisting>
|
||||
</example>
|
||||
|
||||
|
||||
|
||||
<para>Just how random is $RANDOM? The best way to test this is
|
||||
|
|
@ -7837,7 +7972,7 @@ rnumber=$(((RANDOM%30/3+1)*3))
|
|||
a $RANDOM die a few times...</para>
|
||||
|
||||
<example id="randomtest">
|
||||
<title>Rolling the die with RANDOM</title>
|
||||
<title>Rolling a single die with RANDOM</title>
|
||||
<programlisting>&randomtest;</programlisting>
|
||||
</example>
|
||||
|
||||
|
|
@ -8888,13 +9023,24 @@ echo; echo "Keypress was "\"$keypress\""."
|
|||
linkend="echoref">echo</link> to set variables <link
|
||||
linkend="badread0">will fail</link>.</para>
|
||||
|
||||
<para>However, piping the output of <link
|
||||
linkend="catref">cat</link> does seem to work.
|
||||
<programlisting>cat file1 file2 |
|
||||
<para>Yet, piping the output of <link
|
||||
linkend="catref">cat</link> <emphasis>seems</emphasis> to
|
||||
work.</para>
|
||||
|
||||
<para><programlisting>cat file1 file2 |
|
||||
while read line
|
||||
do
|
||||
echo $line
|
||||
done</programlisting></para>
|
||||
|
||||
|
||||
<para>However, as Bjön Eriksson shows:</para>
|
||||
|
||||
<example id="readpipe">
|
||||
<title>Problems reading from a pipe</title>
|
||||
<programlisting>&readpipe;</programlisting>
|
||||
</example>
|
||||
|
||||
</note>
|
||||
|
||||
|
||||
|
|
@ -9071,7 +9217,7 @@ done</programlisting></para>
|
|||
complex version of <link linkend="exprref">expr</link>.</para>
|
||||
|
||||
<example id="ex46">
|
||||
<title>Letting <command>let</command> do some arithmetic.</title>
|
||||
<title>Letting <quote>let</quote> do arithmetic.</title>
|
||||
<programlisting>&ex46;</programlisting>
|
||||
</example>
|
||||
|
||||
|
|
@ -10252,7 +10398,10 @@ wait</programlisting>
|
|||
<token>>></token>), it is commonly used to concatenate
|
||||
files.
|
||||
|
||||
<programlisting>cat filename cat file.1 file.2 file.3 > file.123</programlisting>
|
||||
<programlisting># Uses of 'cat'
|
||||
cat filename # Lists the file.
|
||||
|
||||
cat file.1 file.2 file.3 > file.123 # Combines three files into one.</programlisting>
|
||||
|
||||
The <option>-n</option> option to <command>cat</command>
|
||||
inserts consecutive numbers before all lines of the
|
||||
|
|
@ -10418,7 +10567,7 @@ wait</programlisting>
|
|||
<secondary>mkdir</secondary>
|
||||
</indexterm>
|
||||
<listitem>
|
||||
<para>Make directory, creates a new directory.
|
||||
<para>Make directory, creates a new directory. For example,
|
||||
<userinput>mkdir -p project/programs/December</userinput>
|
||||
creates the named directory. The
|
||||
<replaceable>-p</replaceable> option automatically creates
|
||||
|
|
@ -10485,13 +10634,24 @@ chmod u+s filename
|
|||
<term><command>ln</command></term>
|
||||
<listitem>
|
||||
|
||||
<para>Creates links to pre-existings files. Most often used
|
||||
with the <option>-s</option>, symbolic or
|
||||
<quote>soft</quote> link flag. This permits referencing
|
||||
<para>Creates links to pre-existings files. A <quote>link</quote>
|
||||
is a reference to a file, an alternate name for it.
|
||||
The <command>ln</command> command permits referencing
|
||||
the linked file by more than one name and is a superior
|
||||
alternative to aliasing (see <xref linkend="ex18">).</para>
|
||||
|
||||
<para>The <command>ln</command> command is most often used
|
||||
with the <option>-s</option>, symbolic or
|
||||
<quote>soft</quote> link flag. Without this flag, the command
|
||||
actually creates a full-length copy of the file. With it,
|
||||
<command>ln</command> creates only a reference, a pointer to the
|
||||
file only a few bytes in size. An additional advantage of
|
||||
using the <option>-s</option> flag is that it permits linking
|
||||
across file systems.</para>
|
||||
|
||||
|
||||
<para><userinput>ln -s oldfile newfile</userinput>
|
||||
<para>The syntax of the command is a bit tricky. For example:
|
||||
<userinput>ln -s oldfile newfile</userinput>
|
||||
links the previously existing
|
||||
<filename>oldfile</filename> to the newly created link,
|
||||
<filename>newfile</filename>.</para>
|
||||
|
|
@ -11910,7 +12070,7 @@ tr -d 0-9 <filename
|
|||
</example>
|
||||
|
||||
<example id="du">
|
||||
<title><command>du</command>: DOS to UNIX text file conversion.</title>
|
||||
<title><command>Du</command>: DOS to UNIX text file conversion.</title>
|
||||
<programlisting>&du;</programlisting>
|
||||
</example>
|
||||
|
||||
|
|
@ -12123,16 +12283,37 @@ tr -d 0-9 <filename
|
|||
</indexterm>
|
||||
<indexterm>
|
||||
<primary>command</primary>
|
||||
<secondary>gettext</secondary>
|
||||
<secondary>localization</secondary>
|
||||
</indexterm>
|
||||
<listitem>
|
||||
<para>A GNU utility for <link
|
||||
linkend="localization">localization</link> and
|
||||
translating the text output of programs into
|
||||
foreign languages. While primarily intended for C
|
||||
programs, <command>gettext</command> also finds
|
||||
use in shell scripts. See the <replaceable>info
|
||||
page</replaceable>.</para>
|
||||
|
||||
<para>The GNU <command>gettext</command> package is a set of
|
||||
utilities for <link linkend="localization">localizing</link>
|
||||
and translating the text output of programs into foreign
|
||||
languages. While originally intended for C programs, it
|
||||
now supports quite a number of programming and scripting
|
||||
languages.</para>
|
||||
|
||||
<para>The <command>gettext</command>
|
||||
<emphasis>program</emphasis> works on shell scripts. See
|
||||
the <replaceable>info page</replaceable>.</para>
|
||||
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><anchor id="msgfmtref"><command>msgfmt</command></term>
|
||||
<indexterm>
|
||||
<primary>msgfmt</primary>
|
||||
</indexterm>
|
||||
<indexterm>
|
||||
<primary>command</primary>
|
||||
<secondary>localization</secondary>
|
||||
</indexterm>
|
||||
<listitem>
|
||||
<para>A program for generating binary
|
||||
message catalogs. It is used for <link
|
||||
linkend="localization">localization</link>.</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
|
|
@ -12147,7 +12328,8 @@ tr -d 0-9 <filename
|
|||
</indexterm>
|
||||
<listitem>
|
||||
<para>A utility for converting file(s) to a different encoding
|
||||
(character set). Its chief use is for localization.</para>
|
||||
(character set). Its chief use is for <link
|
||||
linkend="localization">localization</link>.</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
|
|
@ -14609,7 +14791,9 @@ LIMIT_STRING
|
|||
parses command-line options preceded by a <link
|
||||
linkend="dashref">dash</link>. This external command
|
||||
corresponds to the <link linkend="getoptsx">getopts</link>
|
||||
Bash builtin, but it is not nearly as versatile.</para>
|
||||
Bash builtin, but it is not nearly as versatile. However,
|
||||
<command>getopt</command> does permit handling long options
|
||||
by use of the <option>-l</option> flag.</para>
|
||||
|
||||
<example id="ex33a">
|
||||
<title>Using <command>getopt</command> to parse command-line
|
||||
|
|
@ -16409,16 +16593,21 @@ exit 0
|
|||
|
||||
<screen>
|
||||
<prompt>bash$ </prompt><userinput>sar</userinput>
|
||||
<computeroutput>Linux 2.4.7-10 (localhost.localdomain) 12/31/2001
|
||||
<computeroutput>Linux 2.4.9 (brooks.seringas.fr) 09/26/03
|
||||
|
||||
10:30:01 AM CPU %user %nice %system %idle
|
||||
10:40:00 AM all 1.39 0.00 0.77 97.84
|
||||
10:50:00 AM all 76.83 0.00 1.45 21.72
|
||||
11:00:00 AM all 1.32 0.00 0.69 97.99
|
||||
11:10:00 AM all 1.17 0.00 0.30 98.53
|
||||
11:20:00 AM all 0.51 0.00 0.30 99.19
|
||||
06:30:00 PM all 100.00 0.00 100.01 0.00
|
||||
Average: all 1.39 0.00 0.66 97.95</computeroutput>
|
||||
10:30:00 CPU %user %nice %system %iowait %idle
|
||||
10:40:00 all 2.21 10.90 65.48 0.00 21.41
|
||||
10:50:00 all 3.36 0.00 72.36 0.00 24.28
|
||||
11:00:00 all 1.12 0.00 80.77 0.00 18.11
|
||||
Average: all 2.23 3.63 72.87 0.00 21.27
|
||||
|
||||
14:32:30 LINUX RESTART
|
||||
|
||||
15:00:00 CPU %user %nice %system %iowait %idle
|
||||
15:10:00 all 8.59 2.40 17.47 0.00 71.54
|
||||
15:20:00 all 4.07 1.00 11.95 0.00 82.98
|
||||
15:30:00 all 0.79 2.94 7.56 0.00 88.71
|
||||
Average: all 6.33 1.70 14.71 0.00 77.26</computeroutput>
|
||||
</screen>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
|
@ -19733,7 +19922,9 @@ COMMAND7</programlisting>
|
|||
<programlisting>if (set -u; : $variable) 2> /dev/null
|
||||
then
|
||||
echo "Variable is set."
|
||||
fi
|
||||
fi # Variable has been set in current script,
|
||||
#+ or is an an internal Bash variable,
|
||||
#+ or is present in environment (has been exported).
|
||||
|
||||
# Could also be written [[ ${variable-x} != x || ${variable-y} != y ]]
|
||||
# or [[ ${variable-x} != x$variable ]]
|
||||
|
|
@ -20472,6 +20663,9 @@ echo "global_var = $global_var" # global_var = 37
|
|||
script with a segfault.
|
||||
<programlisting>#!/bin/bash
|
||||
|
||||
# Warning: Running this script could possibly lock up your system!
|
||||
# If you're lucky, it will segfault before using up all available memory.
|
||||
|
||||
recursive_function ()
|
||||
{
|
||||
(( $1 < $2 )) && f $(( $1 + 1 )) $2;
|
||||
|
|
@ -20480,14 +20674,16 @@ recursive_function ()
|
|||
}
|
||||
|
||||
recursive_function 1 50000 # Recurse 50,000 levels!
|
||||
# Segfaults, of course.
|
||||
# Most likely segfaults (depending on stack size, set by ulimit -m).
|
||||
|
||||
# Recursion this deep might cause even a C program to segfault,
|
||||
#+ by using up all the memory allotted to the stack.
|
||||
|
||||
# Thanks, S.C.
|
||||
|
||||
exit 0 # This script will not exit normally.</programlisting>
|
||||
echo "This will probably not print."
|
||||
exit 0 # This script will not exit normally.
|
||||
|
||||
# Thanks, Stephane Chazelas.</programlisting>
|
||||
</para></footnote>
|
||||
|
||||
</para>
|
||||
|
|
@ -20754,30 +20950,20 @@ echo ${#string[@]} # 1
|
|||
standard Bash commands and operators have special options adapted
|
||||
for array use.</para>
|
||||
|
||||
<para>
|
||||
<programlisting>array=( zero one two three four five )
|
||||
<example id="arrayops">
|
||||
<title>Various array operations</title>
|
||||
<programlisting>&arrayops;</programlisting>
|
||||
</example>
|
||||
|
||||
echo ${array[0]} # zero
|
||||
echo ${array:0} # zero
|
||||
# Parameter expansion of first element.
|
||||
echo ${array:1} # ero
|
||||
# Parameter expansion of first element,
|
||||
#+ starting at position #1 (2nd character).
|
||||
<para>Many of the standard <link linkend="stringmanip">string
|
||||
operations</link> work on arrays.</para>
|
||||
|
||||
echo ${#array} # 4
|
||||
# Length of first element of array.
|
||||
<example id="arraystrops">
|
||||
<title>String operations on arrays</title>
|
||||
<programlisting>&arraystrops;</programlisting>
|
||||
</example>
|
||||
|
||||
|
||||
|
||||
array2=( [0]="first element" [1]="second element" [3]="fourth element" )
|
||||
|
||||
echo ${array2[0]} # first element
|
||||
echo ${array2[1]} # second element
|
||||
echo ${array2[2]} #
|
||||
# Skipped in initialization, therefore null.
|
||||
echo ${array2[3]} # fourth element</programlisting>
|
||||
</para>
|
||||
|
||||
<para><link linkend="commandsubref">Command substitution</link> can
|
||||
construct the individual elements of an array.</para>
|
||||
|
||||
|
|
@ -20869,11 +21055,22 @@ echo $element_count # 8</programlisting>
|
|||
|
||||
<para>Clever scripting makes it possible to add array operations.</para>
|
||||
|
||||
<example id="arrayassign">
|
||||
<title>Initializing arrays</title>
|
||||
<programlisting>&arrayassign;</programlisting>
|
||||
</example>
|
||||
|
||||
<example id="copyarray">
|
||||
<title>Copying and concatenating arrays</title>
|
||||
<programlisting>©array;</programlisting>
|
||||
</example>
|
||||
|
||||
<example id="arrayappend">
|
||||
<title>More on concatenating arrays</title>
|
||||
<programlisting>&arrayappend;</programlisting>
|
||||
</example>
|
||||
|
||||
|
||||
<para>--</para>
|
||||
|
||||
<para>Arrays permit deploying old familiar algorithms as shell scripts.
|
||||
|
|
@ -22046,7 +22243,7 @@ exit 0</programlisting>
|
|||
|
||||
<para><anchor id="badread0"></para>
|
||||
<para><link linkend="piperef">Piping</link>
|
||||
<command>echo</command>output to a <link
|
||||
<command>echo</command> output to a <link
|
||||
linkend="readref">read</link> may produce unexpected
|
||||
results. In this scenario, the <command>read</command>
|
||||
acts as if it were running in a subshell. Instead, use
|
||||
|
|
@ -23385,7 +23582,7 @@ fi</programlisting>
|
|||
<para>The current version of <emphasis>Bash</emphasis>, the one
|
||||
you have running on your machine, is actually version 2.XX.Y.
|
||||
<screen><prompt>bash$ </prompt><userinput>echo $BASH_VERSION</userinput>
|
||||
<computeroutput>2.05.8(1)-release</computeroutput>
|
||||
<computeroutput>2.05.b.0(1)-release</computeroutput>
|
||||
</screen>
|
||||
This update of the classic Bash scripting language added array
|
||||
variables,
|
||||
|
|
@ -23487,7 +23684,7 @@ fi</programlisting>
|
|||
mortgage calculator, the <ulink
|
||||
url="http://ibiblio.org/pub/Linux/games/amusements/judge-1.0.tar.gz">judge</ulink>
|
||||
Scrabble® adjudicator, and the <ulink
|
||||
url="http://ibiblio.org/pub/Linux/libs/yawl-0.2.tar.gz">yawl</ulink>
|
||||
url="http://ibiblio.org/pub/Linux/libs/yawl-0.3.tar.gz">yawl</ulink>
|
||||
word gaming list package. He got his start in programming using
|
||||
FORTRAN IV on a CDC 3800, but is not the least bit nostalgic
|
||||
for those days.</para>
|
||||
|
|
@ -23498,6 +23695,22 @@ fi</programlisting>
|
|||
</sect1> <!-- About the Author -->
|
||||
|
||||
|
||||
|
||||
<sect1 id="wherehelp">
|
||||
<title>Where to Go For Help</title>
|
||||
|
||||
<para><ulink url="mailto:thegrendel@theriver.com">The author</ulink>
|
||||
will usually, if not too busy (and in a good mood),
|
||||
answer general scripting questions. However, if
|
||||
you have a problem getting a specific script to
|
||||
work, you would be well advised to post to the <ulink
|
||||
url="news:comp.unix.shell">comp.os.unix.shell</ulink> Usenet
|
||||
newsgroup.</para>
|
||||
|
||||
</sect1> <!-- Where to Go For Help -->
|
||||
|
||||
|
||||
|
||||
<sect1 id="toolsused">
|
||||
<title>Tools Used to Produce This Book</title>
|
||||
|
||||
|
|
@ -23646,11 +23859,12 @@ fi</programlisting>
|
|||
were Gabor Kiss, Leopold Toetsch, Peter Tillier, Marcus Berglof,
|
||||
Tony Richardson, Nick Drage (script ideas!), Rich Bartell, Jess
|
||||
Thrysoee, Adam Lazur, Bram Moolenaar, Baris Cicek, Greg Keraunen,
|
||||
Keith Matthews, Sandro Magi, Albert Reiner, Dim Segebart, Rory
|
||||
Winston, Lee Bigelow, Wayne Pollock, <quote>jipe,</quote> Emilio
|
||||
Conti, Dennis Leeuw, Dan Jacobson, Aurelio Marinho Jargas,
|
||||
Edward Scholtz, Jean Helou, Chris Martin, and David Lawyer
|
||||
(himself an author of 4 HOWTOs).</para>
|
||||
Keith Matthews, Sandro Magi, Albert Reiner, Dim Segebart,
|
||||
Rory Winston, Lee Bigelow, Wayne Pollock, <quote>jipe,</quote>
|
||||
Emilio Conti, Dennis Leeuw, Dan Jacobson, Aurelio Marinho Jargas,
|
||||
Edward Scholtz, Jean Helou, Chris Martin, Lee Maschmeyer, Bruno
|
||||
Haible, Sebastien Godard, Bjön Eriksson, Bill Gradwohl,
|
||||
and David Lawyer (himself an author of four HOWTOs).</para>
|
||||
|
||||
<para>My gratitude to <ulink url="mailto:chet@po.cwru.edu">Chet
|
||||
Ramey</ulink> and Brian Fox for writing <command>Bash</command>,
|
||||
|
|
@ -23917,6 +24131,27 @@ fi</programlisting>
|
|||
</abstract>
|
||||
</biblioentry>
|
||||
|
||||
<biblioentry>
|
||||
<authorgroup>
|
||||
<author><firstname>Chet</firstname><surname>Ramey</surname></author>
|
||||
<author><firstname>Brian</firstname><surname>Fox</surname></author>
|
||||
</authorgroup>
|
||||
<title><ulink
|
||||
url="http://www.network-theory.co.uk/bash/manual/">The GNU Bash Reference Manual</ulink></title>
|
||||
<publisher>
|
||||
<publishername>Network Theory Ltd</publishername>
|
||||
</publisher>
|
||||
<copyright>
|
||||
<year>2003</year>
|
||||
</copyright>
|
||||
<isbn>0-9541617-7-7</isbn>
|
||||
<abstract><para>This manual is the definitive reference for
|
||||
GNU Bash. The authors of this manual, Chet Ramey and Brian Fox,
|
||||
are the original developers of GNU Bash. For each copy sold the
|
||||
publisher donates $1 to the Free Software Foundation.</para>
|
||||
</abstract>
|
||||
</biblioentry>
|
||||
|
||||
<biblioentry>
|
||||
<authorgroup>
|
||||
<author><firstname>Arnold</firstname><surname>Robbins</surname></author>
|
||||
|
|
@ -24223,6 +24458,15 @@ fi</programlisting>
|
|||
</abstract>
|
||||
</biblioentry>
|
||||
|
||||
<biblioentry>
|
||||
<abstract>
|
||||
<para><ulink url="mailto:brtompkins@comcast.net">Ben
|
||||
Tomkins</ulink> has created the <ulink
|
||||
url="http://bashnavigator.sourceforge.net">
|
||||
Bash Navigator</ulink> directory management tool.</para>
|
||||
</abstract>
|
||||
</biblioentry>
|
||||
|
||||
<biblioentry>
|
||||
<abstract>
|
||||
<para>Rocky Bernstein is in the process of developing a
|
||||
|
|
@ -24435,6 +24679,30 @@ fi</programlisting>
|
|||
<programlisting>&objoriented;</programlisting>
|
||||
</example>
|
||||
|
||||
|
||||
<para>How do you keep the shell from expanding and reinterpreting
|
||||
strings?</para>
|
||||
|
||||
<example id="protectliteral">
|
||||
<title>Protecting literal strings</title>
|
||||
<programlisting>&protectliteral;</programlisting>
|
||||
</example>
|
||||
|
||||
<para>What if you <emphasis>want</emphasis> the shell to expand
|
||||
and reinterpret strings?</para>
|
||||
|
||||
<example id="unprotectliteral">
|
||||
<title>Unprotecting literal strings</title>
|
||||
<programlisting>&unprotectliteral;</programlisting>
|
||||
</example>
|
||||
|
||||
<para>To end this section, a review of the basics . . . and more.</para>
|
||||
|
||||
<example id="basicsreviewed">
|
||||
<title>Basics Reviewed</title>
|
||||
<programlisting>&basicsreviewed;</programlisting>
|
||||
</example>
|
||||
|
||||
</appendix>
|
||||
<!-- End Contributed Scripts appendix -->
|
||||
|
||||
|
|
@ -25421,7 +25689,15 @@ awk '{print $1 $5 $6}' $filename
|
|||
<command>BEGIN</command>, for a code block to be performed before awk
|
||||
starts processing its input.</para>
|
||||
|
||||
<para>For examples of awk within shell scripts, see:
|
||||
<para>The following example illustrates how <command>awk</command> can
|
||||
add text-parsing tools to a shell script.</para>
|
||||
|
||||
<example id="lettercount">
|
||||
<title>Counting Letter Occurrences</title>
|
||||
<programlisting>&lettercount;</programlisting>
|
||||
</example>
|
||||
|
||||
<para>For simpler examples of awk within shell scripts, see:
|
||||
<orderedlist>
|
||||
<listitem><para><xref linkend="ex44"></para></listitem>
|
||||
<listitem><para><xref linkend="redir4"></para></listitem>
|
||||
|
|
@ -25708,6 +25984,7 @@ exit 0</programlisting>
|
|||
<appendix id="localization">
|
||||
<title>Localization</title>
|
||||
|
||||
|
||||
<para>Localization is an undocumented Bash feature.</para>
|
||||
|
||||
<para>A localized shell script echoes its text output in the
|
||||
|
|
@ -25723,6 +26000,9 @@ exit 0</programlisting>
|
|||
<para>
|
||||
<programlisting>#!/bin/bash
|
||||
# localized.sh
|
||||
# Script by Stephane Chazelas, modified by Bruno Haible
|
||||
|
||||
. gettext.sh
|
||||
|
||||
E_CDERROR=65
|
||||
|
||||
|
|
@ -25732,8 +26012,8 @@ error()
|
|||
exit $E_CDERROR
|
||||
}
|
||||
|
||||
cd $var || error $"Can't cd to %s." "$var"
|
||||
read -p $"Enter the value: " var
|
||||
cd $var || error "`eval_gettext \"Can't cd to \$var.\"`"
|
||||
read -p "`gettext \"Enter the value: \"`" var
|
||||
# ...</programlisting>
|
||||
</para>
|
||||
|
||||
|
|
@ -25762,6 +26042,25 @@ read -p $"Enter the value: " var
|
|||
|
||||
</para>
|
||||
|
||||
<note>
|
||||
<para>Bruno Haible points out:</para>
|
||||
|
||||
<para>Starting with gettext-0.12.2, <command>xgettext -o - localized.sh</command>
|
||||
is recommended instead of <command>bash --dump-po-strings
|
||||
localized.sh</command>, because <command>xgettext</command> . . .</para>
|
||||
|
||||
<para>1. understands the gettext and eval_gettext commands
|
||||
(whereas bash --dump-po-strings understands only its deprecated
|
||||
$"..." syntax)</para>
|
||||
|
||||
<para>2. can extract comments placed by the programmer, intended
|
||||
to be read by the translator.</para>
|
||||
|
||||
<para>This shell code is then not specific to Bash any
|
||||
more; it works the same way with Bash 1.x and other /bin/sh
|
||||
implementations.</para>
|
||||
</note>
|
||||
|
||||
|
||||
<para>Now, build a <filename>language.po</filename>
|
||||
file for each language that the script will be translated
|
||||
|
|
@ -25778,7 +26077,7 @@ msgid "Enter the value: "
|
|||
msgstr "Entrez la valeur : "</programlisting>
|
||||
</para>
|
||||
|
||||
<para>Then, run <command>msgfmt</command>.</para>
|
||||
<para>Then, run <link linkend="msgfmtref">msgfmt</link>.</para>
|
||||
<para><userinput>msgfmt -o localized.sh.mo fr.po</userinput></para>
|
||||
|
||||
<para>Place the resulting <filename>localized.sh.mo</filename> file in the
|
||||
|
|
@ -25821,7 +26120,9 @@ read -p "$(gettext -s "Enter the value: ")" var
|
|||
|
||||
<para>---</para>
|
||||
|
||||
<para>This appendix written by Stephane Chazelas.</para>
|
||||
<para>This appendix written by Stephane Chazelas, with modifications
|
||||
suggested by Bruno Haible, maintainer of GNU
|
||||
<link linkend="gettextref">gettext</link>.</para>
|
||||
|
||||
</appendix>
|
||||
<!-- Localization -->
|
||||
|
|
@ -26698,7 +26999,7 @@ Smith,Tom,404 Polk Ave.,Los Angeles,CA,90003,(213) 879-5612
|
|||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><command>Passwords</command></term>
|
||||
<term><command>Generating Passwords</command></term>
|
||||
<listitem>
|
||||
<para>Generate pseudorandom 8-character passwords, using
|
||||
characters in the ranges [0-9], [A-Z], [a-z]. Each password
|
||||
|
|
@ -26712,6 +27013,59 @@ Smith,Tom,404 Polk Ave.,Los Angeles,CA,90003,(213) 879-5612
|
|||
<variablelist id="exdifficult">
|
||||
<title><anchor id="exdifficult1">Difficult</title>
|
||||
|
||||
<varlistentry>
|
||||
<term><command>Testing Passwords</command></term>
|
||||
<listitem>
|
||||
<para>Write a script to check and validate passwords. The object
|
||||
is to flag <quote>weak</quote> or easily guessed password
|
||||
candidates.</para>
|
||||
|
||||
<para>A trial password will be input to the script as a
|
||||
command line parameter. To be considered acceptable,
|
||||
a password must meet the following minimum qualifications:
|
||||
|
||||
<itemizedlist>
|
||||
<listitem>
|
||||
<para>Minimum length of 8 characters</para>
|
||||
</listitem>
|
||||
|
||||
<listitem>
|
||||
<para>Must contain at least one numeric character</para>
|
||||
</listitem>
|
||||
|
||||
<listitem>
|
||||
<para>Must contain at least one of the following
|
||||
non-alphabetic characters: <token>@</token>,
|
||||
<token>#</token>, <token>$</token>, <token>%</token>,
|
||||
<token>&</token>, <token>*</token>, <token>+</token>,
|
||||
<token>-</token>, <token>=</token></para>
|
||||
</listitem>
|
||||
</itemizedlist></para>
|
||||
|
||||
<para>Optional:
|
||||
|
||||
<itemizedlist>
|
||||
<listitem>
|
||||
<para>Do a dictionary check on every sequence of at least
|
||||
four consecutive alphabetic characters in the password under
|
||||
test. This will eliminate passwords containing embedded
|
||||
<quote>words</quote> found in a standard dictionary.</para>
|
||||
</listitem>
|
||||
|
||||
<listitem>
|
||||
<para>Enable the script to check all the passwords on your
|
||||
system. These may or may not reside in
|
||||
<filename>/etc/passwd</filename>.</para>
|
||||
</listitem>
|
||||
</itemizedlist></para>
|
||||
|
||||
<para>This exercise tests mastery of <link
|
||||
linkend="regexref">Regular Expressions</link>.</para>
|
||||
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
|
||||
<varlistentry>
|
||||
<term><command>Logging File Accesses</command></term>
|
||||
<listitem>
|
||||
|
|
@ -27060,11 +27414,14 @@ fairly detailed rundown on the Playfair Cipher and its solution methods.</progra
|
|||
<appendix id="copyright">
|
||||
<title>Copyright</title>
|
||||
|
||||
<para>The <quote>Advanced Bash-Scripting Guide</quote> is <trademark
|
||||
<para>The <quote>Advanced Bash Scripting Guide</quote> is <trademark
|
||||
class=copyright>copyright </trademark> 2000, by Mendel Cooper. The
|
||||
author also asserts copyright on all previous versions of this
|
||||
document.</para>
|
||||
|
||||
<para>This blanket copyright recognizes and protects the rights of the
|
||||
contributors to this document.</para>
|
||||
|
||||
|
||||
<para>This document may only be distributed subject to the terms
|
||||
and conditions set forth in the Open Publication
|
||||
|
|
@ -27149,10 +27506,11 @@ B. Distribution of the work or derivative of the work in any standard
|
|||
<para>Hyun Jin Cha has done a <ulink
|
||||
url="http://kldp.org/HOWTO/html/Adv-Bash-Scr-HOWTO/index.html">Korean
|
||||
translation</ulink> of version 1.0.11 of this book. Spanish,
|
||||
Portuguese, French, German, Italian, and Chinese translations
|
||||
are underway. If you wish to translate this document into another
|
||||
language, please feel free to do so, subject to the terms stated
|
||||
above. The author wishes to be notified of such efforts.</para>
|
||||
Portuguese, French, German, Italian, Russian, and Chinese
|
||||
translations are also available or in progress. If you wish to
|
||||
translate this document into another language, please feel free
|
||||
to do so, subject to the terms stated above. The author wishes to
|
||||
be notified of such efforts.</para>
|
||||
|
||||
|
||||
</appendix> <!-- End Copyright appendix -->
|
||||
|
|
|
|||
|
|
@ -3,7 +3,7 @@
|
|||
# Adding a second hard drive to system.
|
||||
# Software configuration. Assumes hardware already mounted.
|
||||
# From an article by the author of this document.
|
||||
# in issue #38 of "Linux Gazette", http://www.linuxgazette.com.
|
||||
# In issue #38 of "Linux Gazette", http://www.linuxgazette.com.
|
||||
|
||||
ROOT_UID=0 # This script must be run as root.
|
||||
E_NOTROOT=67 # Non-root exit error.
|
||||
|
|
|
|||
|
|
@ -9,10 +9,11 @@ grep '.......' | # With at least 7 letters,
|
|||
grep '^is' | # starting with 'is'
|
||||
grep -v 's$' | # no plurals
|
||||
grep -v 'ed$' # no past tense verbs
|
||||
# Possible to add many combinations of conditions.
|
||||
|
||||
# Uses "anagram" utility
|
||||
#+ that is part of the author's "yawl" word list package.
|
||||
# http://ibiblio.org/pub/Linux/libs/yawl-0.2.tar.gz
|
||||
# http://ibiblio.org/pub/Linux/libs/yawl-0.3.tar.gz
|
||||
|
||||
exit 0 # End of code.
|
||||
|
||||
|
|
|
|||
|
|
@ -12,7 +12,7 @@ fi
|
|||
|
||||
echo
|
||||
|
||||
index=1
|
||||
index=1 # Initialize count.
|
||||
|
||||
echo "Listing args with \"\$*\":"
|
||||
for arg in "$*" # Doesn't work properly if "$*" isn't quoted.
|
||||
|
|
@ -24,7 +24,8 @@ echo "Entire arg list seen as single word."
|
|||
|
||||
echo
|
||||
|
||||
index=1
|
||||
index=1 # Reset count.
|
||||
# What happens if you forget to do this?
|
||||
|
||||
echo "Listing args with \"\$@\":"
|
||||
for arg in "$@"
|
||||
|
|
@ -36,6 +37,8 @@ echo "Arg list seen as separate words."
|
|||
|
||||
echo
|
||||
|
||||
index=1 # Reset count.
|
||||
|
||||
echo "Listing args with \$* (unquoted):"
|
||||
for arg in $*
|
||||
do
|
||||
|
|
|
|||
|
|
@ -11,27 +11,28 @@
|
|||
# The plot is actually all water, except for the four corners.
|
||||
# (Think of it as a square with an inscribed circle.)
|
||||
#
|
||||
# Let us fire solid iron cannonballs from an old-style cannon
|
||||
# Let us fire iron cannonballs from an old-style cannon
|
||||
#+ at the square of land.
|
||||
# All the shots impact somewhere on the plot of land,
|
||||
#+ either in the lake or on the dry corners.
|
||||
# Since the lake takes up most of the land area,
|
||||
#+ most of the shots will SPLASH! into the water.
|
||||
# Just a few shots will THUD! into solid ground
|
||||
#+ in the far corners of the land.
|
||||
#+ in the four corners of the land.
|
||||
#
|
||||
# If we take enough random, unaimed shots at the plot of land,
|
||||
#+ Then the ratio of SPLASHES to total shots will approximate
|
||||
#+ the value of PI/4.
|
||||
#
|
||||
# The reason for this is that the cannon is actually shooting
|
||||
#+ only at the upper right-hand quadrant of the square.
|
||||
#+ only at the upper right-hand quadrant of the square,
|
||||
#+ i.e., Quadrant I of the Cartesian coordinate plane.
|
||||
# (The previous explanation was a simplification.)
|
||||
#
|
||||
# Theoretically, the more shots taken, the better the fit.
|
||||
# However, a shell script, as opposed to a compiled language
|
||||
#+ with floating-point math built in, requires a few compromises.
|
||||
# This tends to make the simulation less accurate, unfortunately.
|
||||
# This tends to lower the accuracy of the simulation, unfortunately.
|
||||
|
||||
|
||||
DIMENSION=10000 # Length of each side of the plot of land.
|
||||
|
|
@ -86,6 +87,7 @@ do
|
|||
printf "Yc = %4d " $yCoord
|
||||
printf "Distance = %5d " $distance # Distance from
|
||||
#+ center of lake,
|
||||
# the "origin,"
|
||||
#+ coordinate (0,0).
|
||||
|
||||
if [ "$distance" -le "$DIMENSION" ]
|
||||
|
|
@ -106,7 +108,7 @@ done
|
|||
|
||||
echo
|
||||
echo "After $shots shots, PI looks like approximately $Pi."
|
||||
# Tends to run a bit high...
|
||||
# Tends to run a bit high . . .
|
||||
# Probably due to round-off error and imperfect randomness of $RANDOM.
|
||||
echo
|
||||
|
||||
|
|
|
|||
|
|
@ -8,7 +8,7 @@
|
|||
# Thank you, all you good people at LJ.
|
||||
|
||||
|
||||
#Input error in dialog box.
|
||||
# Input error in dialog box.
|
||||
E_INPUT=65
|
||||
# Dimensions of display, input widgets.
|
||||
HEIGHT=50
|
||||
|
|
|
|||
|
|
@ -2,9 +2,9 @@
|
|||
|
||||
# Example "ex72.sh" modified to use encrypted password.
|
||||
|
||||
# Note that this is still somewhat insecure,
|
||||
# Note that this is still rather insecure,
|
||||
#+ since the decrypted password is sent in the clear.
|
||||
# Use something like "ssh" if this is a concern.
|
||||
# Use something like "ssh" if this is a concern.
|
||||
|
||||
E_BADARGS=65
|
||||
|
||||
|
|
|
|||
|
|
@ -4,7 +4,7 @@
|
|||
echo -n "What is your name? "
|
||||
read name # Try to backspace
|
||||
#+ to erase characters of input.
|
||||
# Won't work.
|
||||
# Problems?
|
||||
echo "Your name is $name."
|
||||
|
||||
stty erase '#' # Set "hashmark" (#) as erase character.
|
||||
|
|
@ -12,4 +12,6 @@ echo -n "What is your name? "
|
|||
read name # Use # to erase last character typed.
|
||||
echo "Your name is $name."
|
||||
|
||||
# Warning: Even after the script exits, the new key value remains set.
|
||||
|
||||
exit 0
|
||||
|
|
|
|||
|
|
@ -1,6 +1,7 @@
|
|||
#!/bin/bash
|
||||
|
||||
# Invoke both with and without arguments, and see what happens.
|
||||
# Invoke this script both with and without arguments,
|
||||
#+ and see what happens.
|
||||
|
||||
for a
|
||||
do
|
||||
|
|
|
|||
|
|
@ -10,7 +10,7 @@ do
|
|||
echo "Your favorite veggie is $vegetable."
|
||||
echo "Yuck!"
|
||||
echo
|
||||
break # if no 'break' here, keeps looping forever.
|
||||
break # What happens if there is no 'break' here?
|
||||
done
|
||||
|
||||
exit 0
|
||||
|
|
|
|||
|
|
@ -1,6 +1,9 @@
|
|||
#!/bin/bash
|
||||
# Exercising getopts and OPTIND
|
||||
# Script modified 10/09/03 at the suggestion of Bill Gradwohl.
|
||||
|
||||
# 'getopts' processes command line arguments to script.
|
||||
|
||||
# Here we observe how 'getopts' processes command line arguments to script.
|
||||
# The arguments are parsed as "options" (flags) and associated arguments.
|
||||
|
||||
# Try invoking this script with
|
||||
|
|
@ -10,8 +13,11 @@
|
|||
#
|
||||
# 'scriptname -qr' - Unexpected result, takes "r" as the argument to option "q"
|
||||
# 'scriptname -q -r' - Unexpected result, same as above
|
||||
# 'scriptname -mnop -mnop' - Unexpected result
|
||||
# (OPTIND is unreliable at stating where an option came from).
|
||||
#
|
||||
# If an option expects an argument ("flag:"), then it will grab
|
||||
# whatever is next on the command line.
|
||||
#+ whatever is next on the command line.
|
||||
|
||||
NO_ARGS=0
|
||||
E_OPTERROR=65
|
||||
|
|
@ -28,18 +34,26 @@ fi
|
|||
while getopts ":mnopq:rs" Option
|
||||
do
|
||||
case $Option in
|
||||
m ) echo "Scenario #1: option -m-";;
|
||||
n | o ) echo "Scenario #2: option -$Option-";;
|
||||
p ) echo "Scenario #3: option -p-";;
|
||||
q ) echo "Scenario #4: option -q-, with argument \"$OPTARG\"";;
|
||||
# Note that option 'q' must have an associated argument,
|
||||
# otherwise it falls through to the default.
|
||||
r | s ) echo "Scenario #5: option -$Option-"'';;
|
||||
m ) echo "Scenario #1: option -m- [OPTIND=${OPTIND}]";;
|
||||
n | o ) echo "Scenario #2: option -$Option- [OPTIND=${OPTIND}]";;
|
||||
p ) echo "Scenario #3: option -p- [OPTIND=${OPTIND}]";;
|
||||
q ) echo "Scenario #4: option -q-\
|
||||
with argument \"$OPTARG\" [OPTIND=${OPTIND}]";;
|
||||
# Note that option 'q' must have an associated argument,
|
||||
#+ otherwise it falls through to the default.
|
||||
r | s ) echo "Scenario #5: option -$Option-";;
|
||||
* ) echo "Unimplemented option chosen.";; # DEFAULT
|
||||
esac
|
||||
done
|
||||
|
||||
shift $(($OPTIND - 1))
|
||||
# Decrements the argument pointer so it points to next argument.
|
||||
# Decrements the argument pointer so it points to next argument.
|
||||
# $1 now references the first non option item supplied on the command line
|
||||
#+ if one exists.
|
||||
|
||||
exit 0
|
||||
|
||||
# As Bill Gradwohl states,
|
||||
# "The getopts mechanism allows one to specify: scriptname -mnop -mnop
|
||||
#+ but there is no reliable way to differentiate what came from where
|
||||
#+ by using OPTIND."
|
||||
|
|
|
|||
|
|
@ -1,16 +1,17 @@
|
|||
#!/bin/bash
|
||||
# Using getopt.
|
||||
|
||||
# Try the following when invoking this script.
|
||||
# sh ex33a -a
|
||||
# sh ex33a -abc
|
||||
# sh ex33a -a -b -c
|
||||
# sh ex33a -d
|
||||
# sh ex33a -dXYZ
|
||||
# sh ex33a -d XYZ
|
||||
# sh ex33a -abcd
|
||||
# sh ex33a -abcdZ
|
||||
# sh ex33a -z
|
||||
# sh ex33a a
|
||||
# Try the following when invoking this script:
|
||||
# sh ex33a.sh -a
|
||||
# sh ex33a.sh -abc
|
||||
# sh ex33a.sh -a -b -c
|
||||
# sh ex33a.sh -d
|
||||
# sh ex33a.sh -dXYZ
|
||||
# sh ex33a.sh -d XYZ
|
||||
# sh ex33a.sh -abcd
|
||||
# sh ex33a.sh -abcdZ
|
||||
# sh ex33a.sh -z
|
||||
# sh ex33a.sh a
|
||||
# Explain the results of each of the above.
|
||||
|
||||
E_OPTERR=65
|
||||
|
|
@ -38,7 +39,7 @@ do
|
|||
shift
|
||||
done
|
||||
|
||||
# It is better to use the 'getopts' builtin in a script,
|
||||
# It is usually better to use the 'getopts' builtin in a script,
|
||||
#+ rather than 'getopt'.
|
||||
# See "ex33.sh".
|
||||
|
||||
|
|
|
|||
|
|
@ -1,12 +1,14 @@
|
|||
#!/bin/bash
|
||||
|
||||
# Copy (verbose) all files in current directory
|
||||
# to directory specified on command line.
|
||||
# Copy (verbose) all files in current directory
|
||||
#+ to directory specified on command line.
|
||||
|
||||
E_NOARGS=65
|
||||
|
||||
if [ -z "$1" ] # Exit if no argument given.
|
||||
then
|
||||
echo "Usage: `basename $0` directory-to-copy-to"
|
||||
exit 65
|
||||
exit $E_NOARGS
|
||||
fi
|
||||
|
||||
ls . | xargs -i -t cp ./{} $1
|
||||
|
|
|
|||
|
|
@ -2,25 +2,27 @@
|
|||
|
||||
echo
|
||||
|
||||
let a=11 # Same as 'a=11'
|
||||
let a=a+5 # Equivalent to let "a = a + 5"
|
||||
# (double quotes and spaces make it more readable)
|
||||
echo "11 + 5 = $a"
|
||||
let a=11 # Same as 'a=11'
|
||||
let a=a+5 # Equivalent to let "a = a + 5"
|
||||
# (Double quotes and spaces make it more readable.)
|
||||
echo "11 + 5 = $a" # 16
|
||||
|
||||
let "a <<= 3" # Equivalent to let "a = a << 3"
|
||||
let "a <<= 3" # Equivalent to let "a = a << 3"
|
||||
echo "\"\$a\" (=16) left-shifted 3 places = $a"
|
||||
# 128
|
||||
|
||||
let "a /= 4" # Equivalent to let "a = a / 4"
|
||||
echo "128 / 4 = $a"
|
||||
let "a /= 4" # Equivalent to let "a = a / 4"
|
||||
echo "128 / 4 = $a" # 32
|
||||
|
||||
let "a -= 5" # Equivalent to let "a = a - 5"
|
||||
echo "32 - 5 = $a"
|
||||
let "a -= 5" # Equivalent to let "a = a - 5"
|
||||
echo "32 - 5 = $a" # 27
|
||||
|
||||
let "a = a * 10" # Equivalent to let "a = a * 10"
|
||||
echo "27 * 10 = $a"
|
||||
let "a *= 10" # Equivalent to let "a = a * 10"
|
||||
echo "27 * 10 = $a" # 270
|
||||
|
||||
let "a %= 8" # Equivalent to let "a = a % 8"
|
||||
let "a %= 8" # Equivalent to let "a = a % 8"
|
||||
echo "270 modulo 8 = $a (270 / 8 = 33, remainder $a)"
|
||||
# 6
|
||||
|
||||
echo
|
||||
|
||||
|
|
|
|||
|
|
@ -1,6 +1,6 @@
|
|||
#!/bin/bash
|
||||
|
||||
# Copying a directory tree using cpio.
|
||||
# Copying a directory tree using 'cpio.'
|
||||
|
||||
ARGS=2
|
||||
E_BADARGS=65
|
||||
|
|
@ -15,6 +15,10 @@ source=$1
|
|||
destination=$2
|
||||
|
||||
find "$source" -depth | cpio -admvp "$destination"
|
||||
# Read the man page to decipher these cpio options.
|
||||
# ^^^^^ ^^^^^
|
||||
# Read the 'find' and 'cpio' man page to decipher these options.
|
||||
|
||||
# It may be useful to check the exit status ($?) here
|
||||
#+ to see if everything worked all right.
|
||||
|
||||
exit 0
|
||||
|
|
|
|||
|
|
@ -7,6 +7,6 @@ b=`ls /usr/local/bin` # Get a file listing...
|
|||
echo $b | fmt -w $WIDTH
|
||||
|
||||
# Could also have been done by
|
||||
# echo $b | fold - -s -w $WIDTH
|
||||
# echo $b | fold - -s -w $WIDTH
|
||||
|
||||
exit 0
|
||||
|
|
|
|||
|
|
@ -1,25 +1,29 @@
|
|||
#!/bin/bash
|
||||
# Global and local variables inside a function.
|
||||
|
||||
func ()
|
||||
{
|
||||
local loc_var=23 # Declared local.
|
||||
echo
|
||||
local loc_var=23 # Declared as local variable.
|
||||
echo # Uses the 'local' builtin.
|
||||
echo "\"loc_var\" in function = $loc_var"
|
||||
global_var=999 # Not declared local.
|
||||
global_var=999 # Not declared as local.
|
||||
# Defaults to global.
|
||||
echo "\"global_var\" in function = $global_var"
|
||||
}
|
||||
|
||||
func
|
||||
|
||||
# Now, see if local 'a' exists outside function.
|
||||
# Now, to see if local variable "loc_var" exists outside function.
|
||||
|
||||
echo
|
||||
echo "\"loc_var\" outside function = $loc_var"
|
||||
# "loc_var" outside function =
|
||||
# Nope, $loc_var not visible globally.
|
||||
# $loc_var outside function =
|
||||
# No, $loc_var not visible globally.
|
||||
echo "\"global_var\" outside function = $global_var"
|
||||
# "global_var" outside function = 999
|
||||
# $global_var outside function = 999
|
||||
# $global_var is visible globally.
|
||||
echo
|
||||
|
||||
exit 0
|
||||
# In contrast to C, a Bash variable declared inside a function
|
||||
#+ is local *only* if declared as such.
|
||||
|
|
|
|||
|
|
@ -1,14 +1,17 @@
|
|||
#!/bin/bash
|
||||
# upload.sh
|
||||
|
||||
# Upload file pair (Filename.lsm, Filename.tar.gz)
|
||||
# to incoming directory at Sunsite (ibiblio.org).
|
||||
# Upload file pair (Filename.lsm, Filename.tar.gz)
|
||||
#+ to incoming directory at Sunsite/UNC (ibiblio.org).
|
||||
# Filename.tar.gz is the tarball itself.
|
||||
# Filename.lsm is the descriptor file.
|
||||
|
||||
|
||||
E_ARGERROR=65
|
||||
|
||||
if [ -z "$1" ]
|
||||
then
|
||||
echo "Usage: `basename $0` filename"
|
||||
echo "Usage: `basename $0` Filename-to-upload"
|
||||
exit $E_ARGERROR
|
||||
fi
|
||||
|
||||
|
|
@ -17,8 +20,8 @@ Filename=`basename $1` # Strips pathname out of file name.
|
|||
|
||||
Server="ibiblio.org"
|
||||
Directory="/incoming/Linux"
|
||||
# These need not be hard-coded into script,
|
||||
# but may instead be changed to command line argument.
|
||||
# These need not be hard-coded into script,
|
||||
#+ but may instead be changed to command line argument.
|
||||
|
||||
Password="your.e-mail.address" # Change above to suit.
|
||||
|
||||
|
|
|
|||
|
|
@ -2,6 +2,7 @@
|
|||
# ex74.sh
|
||||
|
||||
# This is a buggy script.
|
||||
# Where, oh where is the error?
|
||||
|
||||
a=37
|
||||
|
||||
|
|
|
|||
|
|
@ -1,8 +1,9 @@
|
|||
#!/bin/bash
|
||||
|
||||
# This is supposed to delete all filenames in current directory
|
||||
# This script is supposed to delete all filenames in current directory
|
||||
#+ containing embedded spaces.
|
||||
# It doesn't work. Why not?
|
||||
# It doesn't work.
|
||||
# Why not?
|
||||
|
||||
|
||||
badname=`ls | grep ' '`
|
||||
|
|
|
|||
|
|
@ -1,4 +1,5 @@
|
|||
#!/bin/bash
|
||||
# Hunting variables with a trap.
|
||||
|
||||
trap 'echo Variable Listing --- a = $a b = $b' EXIT
|
||||
# EXIT is the name of the signal generated upon exit from a script.
|
||||
|
|
|
|||
|
|
@ -3,11 +3,14 @@
|
|||
# String expansion.
|
||||
# Introduced with version 2 of Bash.
|
||||
|
||||
# Strings of the form $'xxx'
|
||||
# have the standard escaped characters interpreted.
|
||||
# Strings of the form $'xxx'
|
||||
#+ have the standard escaped characters interpreted.
|
||||
|
||||
echo $'Ringing bell 3 times \a \a \a'
|
||||
# May only ring once with certain terminals.
|
||||
echo $'Three form feeds \f \f \f'
|
||||
echo $'10 newlines \n\n\n\n\n\n\n\n\n\n'
|
||||
echo $'\102\141\163\150' # Bash
|
||||
# Octal equivalent of characters.
|
||||
|
||||
exit 0
|
||||
|
|
|
|||
|
|
@ -14,3 +14,4 @@ cat -n `basename $0`
|
|||
# Note that 'nl -ba' will also do so.
|
||||
|
||||
exit 0
|
||||
# -----------------------------------------------------------------
|
||||
|
|
|
|||
|
|
@ -27,7 +27,7 @@ FD_DEBUG3=5
|
|||
log() # Writes time and date to log file.
|
||||
{
|
||||
echo "$(date) $*" >&7 # This *appends* the date to the file.
|
||||
# See below.
|
||||
# See below.
|
||||
}
|
||||
|
||||
|
||||
|
|
|
|||
|
|
@ -1,8 +1,9 @@
|
|||
#!/bin/bash
|
||||
# manview.sh: Formats the source of a man page for viewing.
|
||||
|
||||
# This is useful when writing man page source and you want to
|
||||
#+ look at the intermediate results on the fly while working on it.
|
||||
# This script is useful when writing man page source.
|
||||
# It lets you look at the intermediate results on the fly
|
||||
#+ while working on it.
|
||||
|
||||
E_WRONGARGS=65
|
||||
|
||||
|
|
@ -12,8 +13,10 @@ then
|
|||
exit $E_WRONGARGS
|
||||
fi
|
||||
|
||||
# ---------------------------
|
||||
groff -Tascii -man $1 | less
|
||||
# From the man page for groff.
|
||||
# ---------------------------
|
||||
|
||||
# If the man page includes tables and/or equations,
|
||||
#+ then the above code will barf.
|
||||
|
|
|
|||
|
|
@ -1,4 +1,6 @@
|
|||
#!/bin/bash
|
||||
# patt-matching.sh
|
||||
|
||||
# Pattern matching using the # ## % %% parameter substitution operators.
|
||||
|
||||
var1=abcd12345abc6789
|
||||
|
|
@ -6,7 +8,8 @@ pattern1=a*c # * (wild card) matches everything between a - c.
|
|||
|
||||
echo
|
||||
echo "var1 = $var1" # abcd12345abc6789
|
||||
echo "var1 = ${var1}" # abcd12345abc6789 (alternate form)
|
||||
echo "var1 = ${var1}" # abcd12345abc6789
|
||||
# (alternate form)
|
||||
echo "Number of characters in ${var1} = ${#var1}"
|
||||
echo "pattern1 = $pattern1" # a*c (everything between 'a' and 'c')
|
||||
echo
|
||||
|
|
@ -33,7 +36,7 @@ echo '${var1%%pattern2} =' "${var1%%$pattern2}" # a
|
|||
# Longest possible match, strips out last 12 characters abcd12345abc6789
|
||||
# ^^^^ |-------------|
|
||||
|
||||
# Remember, # and ## work from the left end of string,
|
||||
# Remember, # and ## work from the left end (beginning) of string,
|
||||
# % and %% work from the right end.
|
||||
|
||||
echo
|
||||
|
|
|
|||
|
|
@ -6,6 +6,7 @@
|
|||
|
||||
MINARGS=1 # Script needs at least one argument.
|
||||
DATAFILE=./phonebook
|
||||
# A data file named "phonebook" must exist.
|
||||
PROGNAME=$0
|
||||
E_NOARGS=70 # No arguments error.
|
||||
|
||||
|
|
@ -17,6 +18,7 @@ fi
|
|||
|
||||
if [ $# -eq $MINARGS ]; then
|
||||
grep $1 "$DATAFILE"
|
||||
# 'grep' prints an error message if $DATAFILE not present.
|
||||
else
|
||||
( shift; "$PROGNAME" $* ) | grep $1
|
||||
# Script recursively calls itself.
|
||||
|
|
@ -44,4 +46,4 @@ $bash pb.sh Roe Sam
|
|||
Sam Roe 956 E. 8th St., New York, NY 10009 (212) 444-5678
|
||||
|
||||
# When more than one argument passed to script,
|
||||
#+ prints *only* the line(s) containing all the arguments.
|
||||
#+ it prints *only* the line(s) containing all the arguments.
|
||||
|
|
|
|||
|
|
@ -11,7 +11,7 @@ Line[5]="Or just after."
|
|||
# Attribution.
|
||||
Attrib[1]=" Wallace Stevens"
|
||||
Attrib[2]="\"Thirteen Ways of Looking at a Blackbird\""
|
||||
# Above poem is in the Public Domain (copyright expired).
|
||||
# This poem is in the Public Domain (copyright expired).
|
||||
|
||||
for index in 1 2 3 4 5 # Five lines.
|
||||
do
|
||||
|
|
|
|||
|
|
@ -37,9 +37,9 @@ Primes 1
|
|||
|
||||
exit 0
|
||||
|
||||
# Uncomment lines 17 and 25 to help figure out what is going on.
|
||||
# Uncomment lines 16 and 24 to help figure out what is going on.
|
||||
|
||||
# Compare the speed of this algorithm for generating primes
|
||||
# with the Sieve of Eratosthenes (ex68.sh).
|
||||
# Compare the speed of this algorithm for generating primes
|
||||
#+ with the Sieve of Eratosthenes (ex68.sh).
|
||||
|
||||
# Exercise: Rewrite this script without recursion, for faster execution.
|
||||
# Exercise: Rewrite this script without recursion, for faster execution.
|
||||
|
|
|
|||
|
|
@ -3,11 +3,14 @@
|
|||
# Uses the awk rand() function.
|
||||
|
||||
AWKSCRIPT=' { srand(); print rand() } '
|
||||
# Command(s) / parameters passed to awk
|
||||
# Command(s) / parameters passed to awk
|
||||
# Note that srand() reseeds awk's random number generator.
|
||||
|
||||
|
||||
echo -n "Random number between 0 and 1 = "
|
||||
|
||||
echo | awk "$AWKSCRIPT"
|
||||
# What happens if you leave out the 'echo'?
|
||||
|
||||
exit 0
|
||||
|
||||
|
|
@ -17,9 +20,9 @@ exit 0
|
|||
|
||||
# 1) Using a loop construct, print out 10 different random numbers.
|
||||
# (Hint: you must reseed the "srand()" function with a different seed
|
||||
# in each pass through the loop. What happens if you fail to do this?)
|
||||
#+ in each pass through the loop. What happens if you fail to do this?)
|
||||
|
||||
# 2) Using an integer multiplier as a scaling factor, generate random numbers
|
||||
# in the range between 10 and 100.
|
||||
#+ in the range between 10 and 100.
|
||||
|
||||
# 3) Same as exercise #2, above, but generate random integers this time.
|
||||
|
|
|
|||
|
|
@ -9,7 +9,7 @@ RANGE=10
|
|||
MAXVAL=9
|
||||
|
||||
i=$RANDOM
|
||||
let "i %= $RANGE" # Generate a random number between 0 and $MAXVAL.
|
||||
let "i %= $RANGE" # Generate a random number between 0 and $RANGE - 1.
|
||||
|
||||
if [ "$i" -lt "$MAXVAL" ]
|
||||
then
|
||||
|
|
|
|||
|
|
@ -1,4 +1,7 @@
|
|||
#!/bin/bash
|
||||
# reply.sh
|
||||
|
||||
# REPLY is the default value for a 'read' command.
|
||||
|
||||
echo
|
||||
echo -n "What is your favorite vegetable? "
|
||||
|
|
|
|||
|
|
@ -1,6 +1,6 @@
|
|||
#!/bin/bash
|
||||
# str-test.sh: Testing null strings and unquoted strings,
|
||||
# but not strings and sealing wax, not to mention cabbages and kings...
|
||||
# str-test.sh: Testing null strings and unquoted strings,
|
||||
#+ but not strings and sealing wax, not to mention cabbages and kings . . .
|
||||
|
||||
# Using if [ ... ]
|
||||
|
||||
|
|
@ -28,7 +28,7 @@ then
|
|||
echo "String \"string1\" is not null."
|
||||
else
|
||||
echo "String \"string1\" is null."
|
||||
fi # Quote strings within test brackets!
|
||||
fi # Quote strings within test brackets!
|
||||
|
||||
|
||||
echo
|
||||
|
|
@ -45,8 +45,8 @@ fi
|
|||
# However it is good practice to quote it ("$string1").
|
||||
#
|
||||
# As Stephane Chazelas points out,
|
||||
# if [ $string 1 ] has one argument, "]"
|
||||
# if [ "$string 1" ] has two arguments, the empty "$string1" and "]"
|
||||
# if [ $string1 ] has one argument, "]"
|
||||
# if [ "$string1" ] has two arguments, the empty "$string1" and "]"
|
||||
|
||||
|
||||
|
||||
|
|
@ -63,7 +63,7 @@ else
|
|||
echo "String \"string1\" is null."
|
||||
fi
|
||||
# Again, gives correct result.
|
||||
# Still, it is better to quote it ("$string1"), because...
|
||||
# Still, it is better to quote it ("$string1"), because . . .
|
||||
|
||||
|
||||
string1="a = b"
|
||||
|
|
@ -77,4 +77,4 @@ fi
|
|||
# Not quoting "$string1" now gives wrong result!
|
||||
|
||||
exit 0
|
||||
# Also, thank you, Florian Wisser, for the "heads-up".
|
||||
# Thank you, also, Florian Wisser, for the "heads-up".
|
||||
|
|
|
|||
|
|
@ -1,5 +1,5 @@
|
|||
#!/bin/bash
|
||||
# Simulating a two-dimensional array.
|
||||
# twodim.sh: Simulating a two-dimensional array.
|
||||
|
||||
# A two-dimensional array stores rows sequentially.
|
||||
|
||||
|
|
@ -7,7 +7,7 @@ Rows=5
|
|||
Columns=5
|
||||
|
||||
declare -a alpha # char alpha [Rows] [Columns];
|
||||
# Unnecessary declaration.
|
||||
# Unnecessary declaration. Why?
|
||||
|
||||
load_alpha ()
|
||||
{
|
||||
|
|
@ -16,17 +16,18 @@ local index
|
|||
|
||||
|
||||
for i in A B C D E F G H I J K L M N O P Q R S T U V W X Y
|
||||
do
|
||||
do # Use different symbols if you like.
|
||||
local row=`expr $rc / $Columns`
|
||||
local column=`expr $rc % $Rows`
|
||||
let "index = $row * $Rows + $column"
|
||||
alpha[$index]=$i # alpha[$row][$column]
|
||||
alpha[$index]=$i
|
||||
# alpha[$row][$column]
|
||||
let "rc += 1"
|
||||
done
|
||||
|
||||
# Simpler would be
|
||||
# declare -a alpha=( A B C D E F G H I J K L M N O P Q R S T U V W X Y )
|
||||
# but this somehow lacks the "flavor" of a two-dimensional array.
|
||||
# Simpler would be
|
||||
#+ declare -a alpha=( A B C D E F G H I J K L M N O P Q R S T U V W X Y )
|
||||
#+ but this somehow lacks the "flavor" of a two-dimensional array.
|
||||
}
|
||||
|
||||
print_alpha ()
|
||||
|
|
@ -63,12 +64,14 @@ filter () # Filter out negative array indices.
|
|||
{
|
||||
|
||||
echo -n " " # Provides the tilt.
|
||||
# Explain why.
|
||||
|
||||
if [[ "$1" -ge 0 && "$1" -lt "$Rows" && "$2" -ge 0 && "$2" -lt "$Columns" ]]
|
||||
then
|
||||
let "index = $1 * $Rows + $2"
|
||||
# Now, print it rotated.
|
||||
echo -n " ${alpha[index]}" # alpha[$row][$column]
|
||||
echo -n " ${alpha[index]}"
|
||||
# alpha[$row][$column]
|
||||
fi
|
||||
|
||||
}
|
||||
|
|
@ -76,13 +79,13 @@ fi
|
|||
|
||||
|
||||
|
||||
rotate () # Rotate the array 45 degrees
|
||||
{ # ("balance" it on its lower lefthand corner).
|
||||
rotate () # Rotate the array 45 degrees
|
||||
{ #+ ("balance" it on its lower lefthand corner).
|
||||
local row
|
||||
local column
|
||||
|
||||
for (( row = Rows; row > -Rows; row-- )) # Step through the array backwards.
|
||||
do
|
||||
for (( row = Rows; row > -Rows; row-- ))
|
||||
do # Step through the array backwards.
|
||||
|
||||
for (( column = 0; column < Columns; column++ ))
|
||||
do
|
||||
|
|
@ -103,14 +106,14 @@ do
|
|||
|
||||
done
|
||||
|
||||
# Array rotation inspired by examples (pp. 143-146) in
|
||||
# "Advanced C Programming on the IBM PC", by Herbert Mayer
|
||||
# (see bibliography).
|
||||
# Array rotation inspired by examples (pp. 143-146) in
|
||||
#+ "Advanced C Programming on the IBM PC", by Herbert Mayer
|
||||
#+ (see bibliography).
|
||||
|
||||
}
|
||||
|
||||
|
||||
#-----------------------------------------------------#
|
||||
#--------------- Now, let the show begin. ------------#
|
||||
load_alpha # Load the array.
|
||||
print_alpha # Print it out.
|
||||
rotate # Rotate it 45 degrees counterclockwise.
|
||||
|
|
|
|||
|
|
@ -38,7 +38,7 @@ exit 0
|
|||
# Additional notes (from the author of this script):
|
||||
# -------------------------------------------------
|
||||
|
||||
# 1) Linux allows the users option in the /etc/fstab
|
||||
# 1) Linux allows the "users" option in the /etc/fstab
|
||||
# file so that any user can mount removable media.
|
||||
# But, on a server, I like to allow only a few
|
||||
# individuals access to removable media. I find
|
||||
|
|
@ -53,4 +53,3 @@ exit 0
|
|||
# control over which access can be mounted by using this
|
||||
# same technique in separate mntfloppy, mntcdrom,
|
||||
# and mntsamba scripts.
|
||||
|
||||
|
|
|
|||
|
|
@ -3,7 +3,7 @@
|
|||
#
|
||||
# This script filters the output of "strings" by checking it
|
||||
#+ against a standard word list file.
|
||||
# This effectively eliminates all the gibberish and noise,
|
||||
# This effectively eliminates gibberish and noise,
|
||||
#+ and outputs only recognized words.
|
||||
|
||||
# =================================================================
|
||||
|
|
@ -30,7 +30,7 @@ MINSTRLEN=3 # Minimum string length.
|
|||
WORDFILE=/usr/share/dict/linux.words # Dictionary file.
|
||||
# May specify a different
|
||||
#+ word list file
|
||||
#+ of format 1 word per line.
|
||||
#+ of one-word-per-line format.
|
||||
|
||||
|
||||
wlist=`strings "$1" | tr A-Z a-z | tr '[:space:]' Z | \
|
||||
|
|
@ -64,7 +64,9 @@ do
|
|||
continue
|
||||
fi
|
||||
|
||||
grep -Fw $word "$WORDFILE" # Match whole words only.
|
||||
grep -Fw $word "$WORDFILE" # Match whole words only.
|
||||
# ^^^ # "Fixed strings" and
|
||||
#+ "whole words" options.
|
||||
|
||||
done
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue