updated

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

@@ -6,6 +6,123 @@
              http://personal.riverusers.com/~thegrendel/Change.log
 ------------------------------------------------------------------------
 
+Version 3.6
+Pokeberry release, 08/28/05
+
+1) In "Special Characters" chapter:
+   At "-" (redirection from/to stdin or stdout [dash]) entry,
+   corrected comments.
+   (Thank you, Frank Wang.)
+   Replaced flawed first example at "brace expansion" entry.
+   Added quoting comment at "whitespace" entry.
+   
+2) In "Operators" subsection of "Operations and Related Topics" chapter:
+   Removed unnecessary "echo" from modulo operator usage example.
+   (Thank you, Pasha Zubkov.)
+
+3) In "/proc" section of "/dev and /proc" chapter:
+   Added comment to "pid-identifier.sh" example, per Teemu Huovila.
+   (Thanks!)
+
+4) In "Testing and Branching" section of "Loops and Branches" chapter:
+   Changed description of "case" construct from "equivalent of"
+   to "analog to" "switch" in C/C++.
+   (Thank you, Teemu Huovila.)
+
+5) In "Communications Commands" section of "External Commands" chapter:
+   Added "rsync" entry.
+
+6) In "Miscellaneous Commands" section of "External Commands" chapter:
+   Added additional usage example at "jot/seq" entry.
+
+7) In "Internal Commands and Builtins" chapter:
+   Added "testing 'false'" to "false" entry example.
+   (Thank you, Joe Friedrichsen for the suggestion.)
+   At "getopts" entry, made corrections in description of behavior of
+   $GETOPTS.
+   (Thank you, Pharis Monalo.)
+   At "source" entry, added notes about passing arguments to "sourced"
+   file and using a "return" to pass control back to the calling script.
+   Added "caller" entry.
+
+8) In "Contributed Scripts" appendix:
+   Made changes to "whx.sh" script.
+
+9) In "Test Constructs" section of "Tests" chapter:
+   Fixed up "ex.11.sh" example for difference in Bash 3.x behavior.
+   (Thank you, Frank Wang.)
+
+10) In "Internal Variables" section of "Variables Revisited" chapter:
+    Fixed up comments in "t-out.sh" example to reflect changes
+    in Bash 3.x.
+    (Thank you, Frank Wang.)
+    Fixed up explanation of "anomalous" output given by ${PIPESTATUS[@]}
+    in certain situations.
+    (Thank you, Frank Wang, for providing Chet Ramey's explanation.)
+
+11) In "Typing Variables" section of "Variables Revisited" chapter:
+    Added caution + example of how "typeset" restricts the scope of a
+    variable.
+    (Thank you, Michael Iatrou.)
+
+
+12) In "File and Archiving Commands" section of "External Commands" Chapter:
+    At "file" entry, fixed typo (/usrlocal/bin => /usr/local/bin).
+    Fixed error in "strip-comments.sh" example script.
+    (Thank you, Jesse Gough.)
+
+13) In "Complex Commands" section of "External Commands" Chapter:   
+    At "xargs" entry, added extra usage example.
+    At "expr" entry, added example of illegal arithmetic operation.
+
+14) In "Here Documents" chapter:
+    Added "self-document2.sh" example.
+
+15) In "$RANDOM" section of "Variables Revisited" chapter:
+    Added Frank Wang's alternative to jipe's example.
+
+16) In "Quoting" chapter:
+    Split the chapter into introduction and "Quoting Variables" and
+   "Escaping" sections.
+
+    Corrected note about unquoted "grep" . . .
+    Added discussion about quoting correcting echo's appetite for newlines.
+    Clarified explanation of referencing quoted variables
+    and added footnote.
+    Amended tip about double quotes being necessary only to prevent word
+    splitting.
+    (Thank you, Harald Koenig.)
+
+17) In "Local Variables" section of "Functions" chapter:
+    In footnoted example of a segfaulting recursive function,
+    added an "echo" to properly exercise the function.
+    (Thank you, Dr. Roland Sonnenschein.)
+
+18) In "Debugging" chapter:
+    At listing of "Tools for debugging non-working scripts,"
+    added list item for "$LINENO" variable and "caller" builtin.
+
+    At "trap" entry, replaced buggy "multiple-processes.sh" example.
+    (Thank you, Tedman Eng.)
+
+19) In "Copyright" chapter:
+    Updated licensing terms to give the LDP the right to reassign custodianship
+    of the book in the event the author cannot be contacted.
+
+20) In "Bibliography" section:
+    Added entry for Peter Knowles' booklistgen.sh --
+    Sony Librie booklist generator -- making possible
+    Linux access to this neat e-book reader.
+
+21) Corrected spelling of the name of contributor Stéphane Chazelas
+    in multiple places.
+    (Thank you, Bertrand Mollinier Toublet, for pointing out these
+    embarrassing typos.)
+
+22) Various changes and fixups in example scripts.
+
+
+
 Version 3.5
 Boxberry release, 06/05/05
 
@@ -3194,7 +3311,7 @@ In "External Filters, Programs, and Commands" section:
 
 99) Fixed other minor typos in the document.
 
-100) Stephané Chazelas sent in long lists of corrections and suggestions.
+100) Stéphane Chazelas sent in long lists of corrections and suggestions.
        Bug fixes, improvements, and comments on "ex2.sh" example.
        Bug fixes and improvements to "ex3.sh" example.
        Improvement on "ex4.sh", "ex5.sh", and "ex14.sh" examples.

LDP/guide/docbook/abs-guide/README

@@ -48,9 +48,10 @@ is-spammer.sh (comments on lines 4, 35, and 51)
 bashrc (comments on lines 596 and 618)
 commentblock.sh (lines 4 and 23)
 self-document.sh (line 14)
+self-document2.sh (line 8)
 dev-tcp.sh (line 14)
 archiveweblogs.sh (comment in line 4)
-multiple-processes.sh (line 61)
+multiple-processes.sh (line 143)
 directory-info.sh (lines 36 and 166)
 catscripts.sh (lines 12 and 21)
 is_spammer.bash (comments on various lines)
@@ -60,4 +61,4 @@ Hash.lib, (comments in lines lines 103 and 116: & --> &)
 hash-example.sh (comment in line 3: < --> &lt;, > --> &gt;)
 quote-fetch.sh (comment in line 26: &amp; --> &)
 ftpget.sh (comment in line 28)
-whx.sh (comment in line 230)
+whx.sh (comment in line 259)

LDP/guide/docbook/abs-guide/col-totaler.sh

@@ -14,8 +14,13 @@ fi
 filename=$1
 column_number=$2
 
-# Passing shell variables to the awk part of the script is a bit tricky.
+#  Passing shell variables to the awk part of the script is a bit tricky.
-# See the awk documentation for more details.
+#  One method is to strong-quote the Bash-script variable
+#+ within the awk script.
+#     $'$BASH_SCRIPT_VAR'
+#      ^                ^
+#  This is done in the embedded awk script below.
+#  See the awk documentation for more details.
 
 # A multi-line awk script is invoked by:  awk ' ..... '
 

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

@@ -31,8 +31,11 @@ fi
 
 echo
 
-if /usr/bin/[ -z "$1"         # Again, functionally identical to above.
+
-# if /usr/bin/[ -z "$1" ]     # Works, but gives an error message.
+if /usr/bin/[ -z "$1" ]       # Again, functionally identical to above.
+# if /usr/bin/[ -z "$1"       # Works, but gives an error message.
+#                             # Note:
+#                               This has been fixed in Bash, version 3.x.
 then
   echo "No command-line arguments."
 else

LDP/guide/docbook/abs-guide/multiple-processes.sh

@@ -1,8 +1,90 @@
 #!/bin/bash
-# multiple-processes.sh: Run multiple processes on an SMP box.
+# parent.sh
+# Running multiple processes on an SMP box.
+# Author: Tedman Eng
 
-# Script written by Vernia Damiano.
+#  This is the first of two scripts,
-# Used with permission.
+#+ both of which must be present in the current working directory.
+
+
+
+
+LIMIT=$1         # Total number of process to start
+NUMPROC=4        # Number of concurrent threads (forks?)
+PROCID=1         # Starting Process ID
+echo "My PID is $$"
+
+function start_thread() {
+        if [ $PROCID -le $LIMIT ] ; then
+                ./child.sh $PROCID&
+                let "PROCID++"
+        else
+           echo "Limit reached."
+           wait
+           exit
+        fi
+}
+
+while [ "$NUMPROC" -gt 0 ]; do
+        start_thread;
+        let "NUMPROC--"
+done
+
+
+while true
+do
+
+trap "start_thread" SIGRTMIN
+
+done
+
+exit 0
+
+
+
+# ======== Second script follows ========
+
+
+#!/bin/bash
+# child.sh
+# Running multiple processes on an SMP box.
+# This script is called by parent.sh.
+# Author: Tedman Eng
+
+temp=$RANDOM
+index=$1
+shift
+let "temp %= 5"
+let "temp += 4"
+echo "Starting $index  Time:$temp" "$@"
+sleep ${temp}
+echo "Ending $index"
+kill -s SIGRTMIN $PPID
+
+exit 0
+
+
+# ======================= SCRIPT AUTHOR'S NOTES ======================= #
+#  It's not completely bug free.
+#  I ran it with limit = 500 and after the first few hundred iterations,
+#+ one of the concurrent threads disappeared!
+#  Not sure if this is collisions from trap signals or something else.
+#  No doubt someone may spot the bug and will be writing 
+#+ . . . in the future.
+# ===================================================================== #
+
+
+
+# ----------------------------------------------------------------------#
+
+
+
+#################################################################
+# The following is the original script written by Vernia Damiano.
+# Unfortunately, it doesn't work properly.
+#################################################################
+
+#!/bin/bash
 
 #  Must call script with at least one integer parameter
 #+ (number of concurrent processes).
@@ -24,33 +106,33 @@ shift
 PARAMETRI=( "$@" )      # Parameters of each process
 
 function avvia() {
-	local temp
+         local temp
-	local index
+         local index
-	temp=$RANDOM
+         temp=$RANDOM
-	index=$1
+         index=$1
-	shift
+         shift
-	let "temp %= $TEMPO"
+         let "temp %= $TEMPO"
-	let "temp += 1"
+         let "temp += 1"
-	echo "Starting $index Time:$temp" "$@"
+         echo "Starting $index Time:$temp" "$@"
-	sleep ${temp}
+         sleep ${temp}
-	echo "Ending $index"
+         echo "Ending $index"
-	kill -s SIGRTMIN $$
+         kill -s SIGRTMIN $$
 }
 
 function parti() {
-	if [ $INDICE -gt 0 ] ; then
+         if [ $INDICE -gt 0 ] ; then
-		avvia $INDICE "${PARAMETRI[@]}" &
+              avvia $INDICE "${PARAMETRI[@]}" &
-		let "INDICE--"
+                let "INDICE--"
-	else
+         else
-		trap : SIGRTMIN
+                trap : SIGRTMIN
-	fi
+         fi
 }
 
 trap parti SIGRTMIN
 
 while [ "$NUMPROC" -gt 0 ]; do
-	parti;
+         parti;
-	let "NUMPROC--"
+         let "NUMPROC--"
 done
 
 wait

LDP/guide/docbook/abs-guide/pid-identifier.sh

@@ -18,6 +18,10 @@ pidno=$( ps ax | grep $1 | awk '{ print $1 }' | grep $1 )
 # Checks for pid in "ps" listing, field #1.
 # Then makes sure it is the actual process, not the process invoked by this script.
 # The last "grep $1" filters out this possibility.
+#
+#    pidno=$( ps ax | awk '{ print $1 }' | grep $1 )
+#    also works, as Teemu Huovila, points out.
+
 if [ -z "$pidno" ]  # If, after all the filtering, the result is a zero-length string,
 then                # no running process corresponds to the pid given.
   echo "No such process running."

LDP/guide/docbook/abs-guide/strip-comments.sh

@@ -31,7 +31,7 @@ fi
 #--------
 sed '
 /^\/\*/d
-/.*\/\*/d
+/.*\*\//d
 ' $1
 #--------
 # Easy to understand if you take several hours to learn sed fundamentals.
@@ -41,7 +41,7 @@ sed '
 #+ case where line of code has a comment following it on same line.
 #  This is left as a non-trivial exercise.
 
-#  Also, the above code deletes lines with a "*/" or "/*",
+#  Also, the above code deletes non-comment lines with a "*/" --
 #+ not a desirable result.
 
 exit 0

LDP/guide/docbook/abs-guide/t-out.sh

@@ -6,10 +6,13 @@
 TIMELIMIT=4         # 4 seconds
 
 read -t $TIMELIMIT variable <&1
+#                           ^^^
+#  In this instance, "<&1" is needed for Bash 1.x and 2.x,
+#  but unnecessary for Bash 3.x.
 
 echo
 
-if [ -z "$variable" ]
+if [ -z "$variable" ]  # Is null?
 then
   echo "Timed out, variable still unset."
 else  
@@ -17,8 +20,3 @@ else
 fi  
 
 exit 0
-
-# Exercise for the reader:
-# -----------------------
-# Why is the redirection (<&1) necessary in line 8?
-# What happens if it is omitted?

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

@@ -12,6 +12,7 @@
 E_BADARGS=65        # Missing command-line arg.
 E_NOHOST=66         # Host not found.
 E_TIMEOUT=67        # Host lookup timed out.
+E_UNDEF=68          # Some other (undefined) error.
 HOSTWAIT=10         # Specify up to 10 seconds for host query reply.
                     # The actual wait may be a bit longer.
 OUTFILE=whois.txt   # Output file.
@@ -34,6 +35,8 @@ else
   IPADDR="$1"                         # Command-line arg was IP address.
 fi
 
+echo; echo "IP Address is: "$IPADDR""; echo
+
 if [ -e "$OUTFILE" ]
 then
   rm -f "$OUTFILE"
@@ -42,7 +45,15 @@ fi
 
 
 #  Sanity checks.
-#  ==============
+#  (This section needs more work.)
+#  ===============================
+if [ -z "$IPADDR" ]
+# No response.
+then
+  echo "Host not found!"
+  exit $E_NOHOST    # Bail out.
+fi
+
 if [[ "$IPADDR" =~ "^[;;]" ]]
 #  ;; connection timed out; no servers could be reached
 then
@@ -63,11 +74,11 @@ then
   echo "Host not found!"
   exit $E_NOHOST    # Bail out.
 fi
-#  ==============
 
 
 
-# ========== Main body of script ==========
+
+# ======================== Main body of script ========================
 
 AFRINICquery() {
 #  Define the function that queries AFRINIC. Echo a notification to the
@@ -179,9 +190,27 @@ RIPEquery() {
 #  * octet2 is the second most significant octet
 
 
+
+
 slash8=`echo $IPADDR | cut -d. -f 1`
+  if [ -z "$slash8" ]  # Yet another sanity check.
+  then
+    echo "Undefined error!"
+    exit $E_UNDEF
+  fi
 slash16=`echo $IPADDR | cut -d. -f 1-2`
+#                             ^ Period specified as 'cut" delimiter.
+  if [ -z "$slash16" ]
+  then
+    echo "Undefined error!"
+    exit $E_UNDEF
+  fi
 octet2=`echo $slash16 | cut -d. -f 2`
+  if [ -z "$octet2" ]
+  then
+    echo "Undefined error!"
+    exit $E_UNDEF
+  fi
 
 
 #  Check for various odds and ends of reserved space.
@@ -241,5 +270,7 @@ exit 0
 
 #@  ABS Guide author comments:
 #@  Nothing fancy here, but still a very useful tool for hunting spammers.
-#@  Sure, the script can be cleaned up a bit (exercise for reader),
+#@  Sure, the script can be cleaned up some, and it's still a bit buggy,
-#@+ but still, it's a nice piece of coding by Walter Dnes.
+#@+ (exercise for reader), but all the same, it's a nice piece of coding
+#@+ by Walter Dnes.
+#@  Thank you!