updated

LDP/guide/docbook/abs-guide/Change.log

@@ -6,6 +6,124 @@
              http://personal.riverusers.com/~thegrendel/Change.log
 ------------------------------------------------------------------------
 
+Intermediate release.
+Working toward version 4.0, Winterberry release.
+
+1) "System and Administrative Commands" chapter:
+   Added "gnome-mount" entry.
+   Modified "command" entry to eliminate ambiguity.
+   At "uname" entry, reordered usage example.
+   At "watch" entry, noted that piping output of "watch command" to
+     "grep" doesn't work.
+   In "Filesystem" subsection,
+     At "lockfile" entry, additional comment in in-line example script.
+   In "Job Control" subsection,
+     Added "killall" entry.
+     At "nice" entry, elaborated on "renice," "snice," and "skill."
+
+2) In "Communications Commands" section of "External Commands" chapter:
+   At "ping" entry, added in-line example script.
+
+3) In "Text Processing" section of "External Commands" Chapter:   
+   At "tsort" entry, added material.
+
+4) In "Arrays" chapter:
+   Noted an exception to 'array2=( "${array1[@]}" )' array copying method.
+   (Thank you, Jochen, DeSmet.)
+   Extended "empty-array.sh"
+   (Thank you, Omair Eshkenazi.)
+
+5) In "Tests" chapter:
+     In "Test Constructs" section:
+     Fixed comment typos in "broken-links.sh" example.
+     (Thank you, Omair Eshkenazi.)
+     Added material to note about "test" builtin and /usr/bin/test
+     not being equivalent.
+     In "Other Comparison Operators" section:
+     Rewrote the (short) intro.
+     In "Test Your Knowledge of Tests" section:
+     Updated intro to example snippet.
+
+6) In "$RANDOM" section of "Variables Revisited" chapter:
+   Fixed typo in comment in Jipe's in-line example.
+   Added comment to "random-between.sh" example.
+   (Thank you, Omair Eshkenazi, for both of the above.)
+
+7) In the "Security Issues Section" of the "Miscellany" chapter:
+   Fixed typo in second paragraph.
+   (Thank you, Omair Eshkenazi.)
+
+8) In "List Constructs" chapter:
+   Modified "and list" setting variable to default value in-line example.
+   (Thank you, Omair Eshkenazi.)
+
+9) In "Job Control Commands" section of
+  "Internal Commands and Builtins" chapter:
+   At "kill" entry, added comment about additional file giving signal
+   listing.
+
+10) In "Time/Date Commands" section of "External Commands" chapter:
+    At "touch" entry, added tip about not overwriting files.
+
+11) In "Internal Commands and Builtins" chapter:
+    Added short usage examples to "true" and "false" entries.
+
+12) In "Bash, version 3" section of "Bash, versions 2 and 3" chapter:
+    Added "pipefail" option.
+    Also added this to table in "Options" chapter.
+    At {x..y} "braces expansion operator entry,
+    added a simple "echo" using this.
+    (Thank you, Damon Puncer, for the suggestion.)
+
+13) In "File and Archiving Commands" section of "External Commands" Chapter:
+    At "diff" entry, added note about "diffstat."
+    Moved "sum/cksum/md5sum/sha1sum" and "shred" entries
+    to "Encoding and Encryption" subsection.
+
+14) In "Contributed Scripts" appendix:
+    Added "ha.sh" hashing script.
+    (Thank you, Oliver Beckstein.)
+    Added comments to "fifo.sh" script.
+    (Thank you, Omair Eshkenazi.)
+    More explicit reference to Mark Moraes copyright before
+    his two scripts.
+
+15) Moved "Here Documents" chapter from "Beyond the Basics" section to
+   "Advanced Topics" section.
+
+16) Moved "I/O Redirection" chapter from "Beyond the Basics" section to
+   "Advanced Topics" section.
+
+17) In "/dev" section of "/dev and /proc" chapter:
+    Added material to "socket" footnote.
+
+18) Split off the three "Command" chapters into a different Part.
+    Put an alphabetical command cross-reference into the Introduction
+    to that Part.
+    >> This is a major reorganization of the document. <<
+
+19) In "Special Characters" chapter:
+    Added "extended brace expansion" (Bash 3+) entry.
+    Added "{} -- placeholder for text after "xargs -i" . . .
+
+20) In "Reference Cards" appendix:
+    In "Miscellaneous Constructs" table:
+      Added "extended brace expansion" (Bash 3+) entry.
+      Added "{}" (text replacement) entry.
+      Added more hypertext links.
+      Cleanups.
+
+21) Delineated all references to "root user" with <firstterm> tags.
+
+22) Changed many of the <emphasis> tags in the document
+    to more appropriate <firstterm>, <filename>, and <varname>, etc.
+
+23) Changed certain of the <varname> tags to the more appropriate <parameter>.
+
+24) Various minor fixups on example scripts.
+
+
+
 Version 3.9
 Spiceberry release, 05/15/06
 
@@ -114,7 +232,7 @@ Blaeberry release, 02/26/06
    Fixed minor typo at "${parameter:+alt_value}" example.
    (Thank you, Jemshad O K)
 
-8) Partitioned  "Security Section" of the "Miscellany" chapter
+8) Partitioned  "Security Issues Section" of the "Miscellany" chapter
    into two subsections.
    Added subsection about "shc" utility for compiling script source.
 
@@ -2289,7 +2407,7 @@ Version 1.4 (minor update)
     Added "Passwords" exercise ("Intermediate" section).
     Added "Fog Index" exercise ("Difficult" section).
 
-13) In the "Security Section" of the "Miscellany" chapter:
+13) In the "Security Issues Section" of the "Miscellany" chapter:
     Added 'Unix Scripting Malware' reference to the footnote.
 
 14) In "Starting off with a Sha-Bang" chapter,

LDP/guide/docbook/abs-guide/Moraes-COPYRIGHT

@@ -1,5 +1,7 @@
 The following is the mandatory copyright notice for the two included
-"contrib" scripts by Mark Moraes, "behead.sh" and "ftpget.sh".
+"contrib" scripts by Mark Moraes, "behead.sh" and "ftpget.sh". It is part
+of the combined HTML/source tarball of the _ABS Guide_, and included by
+reference in the PDF version.
 
 
 /*

LDP/guide/docbook/abs-guide/blank-rename.sh

@@ -12,7 +12,7 @@ do
      echo "$filename" | grep -q " "         #  Check whether filename
      if [ $? -eq $FOUND ]                   #+ contains space(s).
      then
-       fname=$filename                      # Strip off path.
+       fname=$filename                      # Yes, this filename needs work.
        n=`echo $fname | sed -e "s/ /_/g"`   # Substitute underscore for blank.
        mv "$fname" "$n"                     # Do the actual renaming.
        let "number += 1"

LDP/guide/docbook/abs-guide/broken-link.sh

@@ -19,16 +19,16 @@
 ##############################################################
 
 
-#If no args are passed to the script set directorys to search 
-#to current directory.  Otherwise set the directorys to search 
-#to the agrs passed.
+#If no args are passed to the script set directories-to-search 
+#to current directory.  Otherwise set the directories-to-search 
+#to the args passed.
 ####################
 [ $# -eq 0 ] && directorys=`pwd` || directorys=$@
 
 #Setup the function linkchk to check the directory it is passed 
 #for files that are links and don't exist, then print them quoted.
 #If one of the elements in the directory is a subdirectory then 
-#send that send that subdirectory to the linkcheck function.
+#send that subdirectory to the linkcheck function.
 ##########
 linkchk () {
     for element in $1/*; do

LDP/guide/docbook/abs-guide/days-between.sh

@@ -88,7 +88,7 @@ day_index ()          # Gauss' Formula:
 }  
 
 
-calculate_difference ()            # Difference between to day indices.
+calculate_difference ()            # Difference between two day indices.
 {
   let "diff = $1 - $2"             # Global variable.
 }  

LDP/guide/docbook/abs-guide/empty-array.sh

@@ -2,14 +2,15 @@
 # empty-array.sh
 
 #  Thanks to Stephane Chazelas for the original example,
-#+ and to Michael Zick for extending it.
+#+ and to Michael Zick and Omair Eshkenazi for extending it.
 
 
 # An empty array is not the same as an array with empty elements.
 
-array0=( first second third )
-array1=( '' )   # "array1" consists of one empty element.
-array2=( )      # No elements . . . "array2" is empty.
+  array0=( first second third )
+  array1=( '' )   # "array1" consists of one empty element.
+  array2=( )      # No elements . . . "array2" is empty.
+  array3=(   )    # What about this array?
 
 echo
 ListArray()
@@ -18,14 +19,17 @@ echo
 echo "Elements in array0:  ${array0[@]}"
 echo "Elements in array1:  ${array1[@]}"
 echo "Elements in array2:  ${array2[@]}"
+echo "Elements in array3:  ${array3[@]}"
 echo
 echo "Length of first element in array0 = ${#array0}"
 echo "Length of first element in array1 = ${#array1}"
 echo "Length of first element in array2 = ${#array2}"
+echo "Length of first element in array3 = ${#array3}"
 echo
 echo "Number of elements in array0 = ${#array0[*]}"  # 3
 echo "Number of elements in array1 = ${#array1[*]}"  # 1  (Surprise!)
 echo "Number of elements in array2 = ${#array2[*]}"  # 0
+echo "Number of elements in array3 = ${#array3[*]}"  # 0
 }
 
 # ===================================================================
@@ -38,6 +42,7 @@ ListArray
 array0=( "${array0[@]}" "new1" )
 array1=( "${array1[@]}" "new1" )
 array2=( "${array2[@]}" "new1" )
+array3=( "${array3[@]}" "new1" )
 
 ListArray
 
@@ -45,6 +50,7 @@ ListArray
 array0[${#array0[*]}]="new2"
 array1[${#array1[*]}]="new2"
 array2[${#array2[*]}]="new2"
+array3[${#array3[*]}]="new2"
 
 ListArray
 
@@ -56,7 +62,7 @@ echo
 echo "Stack height for array2 = $height"
 
 # The 'pop' is:
-unset array2[${#array2[@]}-1]	#  Arrays are zero-based,
+unset array2[${#array2[@]}-1]   #  Arrays are zero-based,
 height=${#array2[@]}            #+ which means first element has index 0.
 echo
 echo "POP"
@@ -66,7 +72,7 @@ ListArray
 
 # List only 2nd and 3rd elements of array0.
 from=1		# Zero-based numbering.
-to=2		#
+to=2
 array3=( ${array0[@]:1:2} )
 echo
 echo "Elements in array3:  ${array3[@]}"

LDP/guide/docbook/abs-guide/erase.sh

@@ -12,6 +12,7 @@ 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
+
+# Even after the script exits, the new key value remains set.
+# Exercise: How would you reset the erase character to the default value?

LDP/guide/docbook/abs-guide/ex11.sh

@@ -11,7 +11,8 @@ fi
 
 echo
 
-if /usr/bin/test -z "$1"      # Same result as "test" builtin".
+if /usr/bin/test -z "$1"      # Equivalent to "test" builtin.
+#  ^^^^^^^^^^^^^              # Specifying full pathname.
 then
   echo "No command-line arguments."
 else

LDP/guide/docbook/abs-guide/ex24.sh

@@ -1,5 +1,5 @@
 #!/bin/bash
-# Faxing (must have 'fax' installed).
+# Faxing (must have 'efax' package installed).
 
 EXPECTED_ARGS=2
 E_BADARGS=65
@@ -14,24 +14,26 @@ fi
 
 if [ ! -f "$2" ]
 then
-  echo "File $2 is not a text file"
+  echo "File $2 is not a text file."
+  #     File is not a regular file, or does not exist.
   exit $E_BADARGS
 fi
   
 
-fax make $2              # Create fax formatted files from text files.
+fax make $2              #  Create fax formatted files from text files.
 
-for file in $(ls $2.0*)  # Concatenate the converted files.
-                         # Uses wild card in variable list.
+for file in $(ls $2.0*)  #  Concatenate the converted files.
+                         #  Uses wild card (filename "globbing")
+			 #+ in variable list.
 do
   fil="$fil $file"
 done  
 
-efax -d /dev/ttyS3 -o1 -t "T$1" $fil   # Do the work.
+efax -d /dev/ttyS3 -o1 -t "T$1" $fil   # Finally, do the work.
 
 
-# As S.C. points out, the for-loop can be eliminated with
-#    efax -d /dev/ttyS3 -o1 -t "T$1" $2.0*
-# but it's not quite as instructive [grin].
+#  As S.C. points out, the for-loop can be eliminated with
+#     efax -d /dev/ttyS3 -o1 -t "T$1" $2.0*
+#+ but it's not quite as instructive [grin].
 
 exit 0

LDP/guide/docbook/abs-guide/ex41.sh

@@ -12,7 +12,7 @@ LINES=5
 ( date; uname -a ) >>logfile
 # Time and machine name
 echo --------------------------------------------------------------------- >>logfile
-tail -$LINES /var/log/messages | xargs |  fmt -s >>logfile
+tail -$LINES /var/log/messages | xargs | fmt -s >>logfile
 echo >>logfile
 echo >>logfile
 

LDP/guide/docbook/abs-guide/fc4upd.sh

@@ -63,7 +63,7 @@ EXCLUDE=(
 
 init () {
     # Let pipe command return possible rsync error, e.g., stalled network.
-    set -o pipefail
+    set -o pipefail                     # Newly introduced in Bash, version 3.
 
     TMP=${TMPDIR:-/tmp}/${0##*/}.$$     # Store refined download list.
     trap "{

LDP/guide/docbook/abs-guide/fifo.sh

@@ -15,9 +15,9 @@
   
   # ==> 'su xyz' runs commands as user "xyz".
   # ==> 'ssh' invokes secure shell (remote login client).
-  su xyz -c "ssh $THERE \"cat >/home/xyz/backup/${HERE}-daily.tar.gz\" < /pipe"&
+  su xyz -c "ssh $THERE \"cat > /home/xyz/backup/${HERE}-daily.tar.gz\" < /pipe"&
   cd /
-  tar -czf - bin boot dev etc home info lib man root sbin share usr var >/pipe
+  tar -czf - bin boot dev etc home info lib man root sbin share usr var > /pipe
   # ==> Uses named pipe, /pipe, to communicate between processes:
   # ==> 'tar/gzip' writes to /pipe and 'ssh' reads from /pipe.
 
@@ -27,5 +27,8 @@
   # ==>+ as opposed to an "anonymous pipe", with |?
   # ==>  Will an anonymous pipe even work here?
 
+  # ==>  Is it necessary to delete the pipe before exiting the script?
+  # ==>  How could that be done?
+
 
   exit 0

LDP/guide/docbook/abs-guide/ftpget.sh

@@ -56,7 +56,8 @@ if [ $? != 0 ]; then
 	exit $E_BADARGS
 fi
 shift
-trap 'rm -f ${TMPFILE} ; exit' 0 1 2 3 15
+trap 'rm -f ${TMPFILE} ; exit' 0   1     2              3        15
+# ==>                   Signals:   HUP   INT (Ctl-C)    QUIT     TERM
 # ==> Delete tempfile in case of abnormal exit from script.
 echo "user anonymous ${USER-gnu}@${SITE} > ${TMPFILE}"
 # ==> Added quotes (recommended in complex echoes).

LDP/guide/docbook/abs-guide/kill-byname.sh

@@ -33,3 +33,6 @@ ps ax | grep "$PROCESS_NAME" | awk '{print $1}' | xargs -i kill {} 2&>/dev/null
 # -----------------------------------------------------------
 
 exit $?
+
+#  The "killall" command has the same effect as this script,
+#+ but using it is not quite as educational.

LDP/guide/docbook/abs-guide/kill-process.sh

@@ -27,7 +27,9 @@ kill $t                  # May need 'kill -9' for stubborn process.
 
 
 # This entire script could be replaced by
-#    kill $(pidof -x process_name)
+#        kill $(pidof -x process_name)
+# or
+#        killall process_name
 # but it would not be as instructive.
 
 exit 0

LDP/guide/docbook/abs-guide/random-between.sh

@@ -93,6 +93,8 @@ randomBetween() {
    #  ---------------------------------------------------------------------
 
    spread=$((max-min))
+   #  Omair Eshkenazi points out that this test is unnecessary,
+   #+ since max and min have already been switched around.
    [ ${spread} -lt 0 ] && spread=$((0-spread))
    let spread+=divisibleBy
    randomBetweenAnswer=$(((RANDOM%spread)/divisibleBy*divisibleBy+min))   

LDP/guide/docbook/abs-guide/read-novar.sh

@@ -24,3 +24,7 @@ echo "\"var\" = "$var""
 echo
 
 exit 0
+
+#  This example is similar to the "reply.sh" script.
+#  However, this one shows that $REPLY is available
+#+ even after a 'read' to a variable in the conventional way.

LDP/guide/docbook/abs-guide/wgetter2.bash

@@ -179,6 +179,7 @@ read Wopts
 # Read in the options to be passed to wget.
 
 Woptions=" $Wopts"
+#         ^  Why the leading space?
 # Assign to another variable.
 # Just for fun, or something . . .