contributed-scripts.html

一本完整的描述Unix Shell 编程的工具书的所有范例

 279 echo "Generation $generation  -  $alive alive"
 280 
 281 if [ "$alive" -eq 0 ]
 282 then
 283   echo
 284   echo "Premature exit: no more cells alive!"
 285   exit $NONE_ALIVE        #  No point in continuing
 286 fi                        #+ if no live cells.
 287 
 288 }
 289 
 290 
 291 # =========================================================
 292 
 293 # main ()
 294 
 295 # Load initial array with contents of startup file.
 296 initial=( `cat "$startfile" | sed -e '/#/d' | tr -d '\n' |\
 297 sed -e 's/\./\. /g' -e 's/_/_ /g'` )
 298 # Delete lines containing '#' comment character.
 299 # Remove linefeeds and insert space between elements.
 300 
 301 clear          # Clear screen.
 302 
 303 echo #         Title
 304 echo "======================="
 305 echo "    $GENERATIONS generations"
 306 echo "           of"
 307 echo "\"Life in the Slow Lane\""
 308 echo "======================="
 309 
 310 
 311 # -------- Display first generation. --------
 312 Gen0=`echo ${initial[@]}`
 313 display "$Gen0"           # Display only.
 314 echo; echo
 315 echo "Generation $generation  -  $alive alive"
 316 # -------------------------------------------
 317 
 318 
 319 let "generation += 1"     # Increment generation count.
 320 echo
 321 
 322 # ------- Display second generation. -------
 323 Cur=`echo ${initial[@]}`
 324 next_gen "$Cur"          # Update & display.
 325 # ------------------------------------------
 326 
 327 let "generation += 1"     # Increment generation count.
 328 
 329 # ------ Main loop for displaying subsequent generations ------
 330 while [ "$generation" -le "$GENERATIONS" ]
 331 do
 332   Cur="$avar"
 333   next_gen "$Cur"
 334   let "generation += 1"
 335 done
 336 # ==============================================================
 337 
 338 echo
 339 
 340 exit 0
 341 
 342 # --------------------------------------------------------------
 343 
 344 # The grid in this script has a "boundary problem."
 345 # The the top, bottom, and sides border on a void of dead cells.
 346 # Exercise: Change the script to have the grid wrap around,
 347 # +         so that the left and right sides will "touch,"      
 348 # +         as will the top and bottom.
 349 #
 350 # Exercise: Create a new "gen0" file to seed this script.
 351 #           Use a 12 x 16 grid, instead of the original 10 x 10 one.
 352 #           Make the necessary changes to the script,
 353 #+          so it will run with the altered file.
 354 #
 355 # Exercise: Modify this script so that it can determine the grid size
 356 #+          from the "gen0" file, and set any variables necessary
 357 #+          for the script to run.
 358 #           This would make unnecessary any changes to variables
 359&nbsp;#+          in the script for an altered grid size.</PRE
></TD
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><HR></DIV
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="GEN0DATA"
></A
><P
><B
>Example A-11. Data file for <SPAN
CLASS="QUOTE"
>"Game of Life"</SPAN
></B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>   1&nbsp;# This is an example "generation 0" start-up file for "life.sh".
   2&nbsp;# --------------------------------------------------------------
   3&nbsp;#  The "gen0" file is a 10 x 10 grid using a period (.) for live cells,
   4&nbsp;#+ and an underscore (_) for dead ones. We cannot simply use spaces
   5&nbsp;#+ for dead cells in this file because of a peculiarity in Bash arrays.
   6&nbsp;#  [Exercise for the reader: explain this.]
   7&nbsp;#
   8&nbsp;# Lines beginning with a '#' are comments, and the script ignores them.
   9&nbsp;__.__..___
  10&nbsp;___._.____
  11&nbsp;____.___..
  12&nbsp;_._______.
  13&nbsp;____._____
  14&nbsp;..__...___
  15&nbsp;____._____
  16&nbsp;___...____
  17&nbsp;__.._..___
  18&nbsp;_..___..__</PRE
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><HR></DIV
><P
>+++</P
><P
>The following two scripts are by Mark Moraes of the University
    of Toronto. See the enclosed file <SPAN
CLASS="QUOTE"
>"Moraes-COPYRIGHT"</SPAN
>
    for permissions and restrictions.</P
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="BEHEAD"
></A
><P
><B
>Example A-12. <B
CLASS="COMMAND"
>behead</B
>: Removing mail and news message headers
      </B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>   1&nbsp;#! /bin/sh
   2&nbsp;# Strips off the header from a mail/News message i.e. till the first
   3&nbsp;# empty line
   4&nbsp;# Mark Moraes, University of Toronto
   5&nbsp;
   6&nbsp;# ==&#62; These comments added by author of this document.
   7&nbsp;
   8&nbsp;if [ $# -eq 0 ]; then
   9&nbsp;# ==&#62; If no command line args present, then works on file redirected to stdin.
  10&nbsp;	sed -e '1,/^$/d' -e '/^[ 	]*$/d'
  11&nbsp;	# --&#62; Delete empty lines and all lines until 
  12&nbsp;	# --&#62; first one beginning with white space.
  13&nbsp;else
  14&nbsp;# ==&#62; If command line args present, then work on files named.
  15&nbsp;	for i do
  16&nbsp;		sed -e '1,/^$/d' -e '/^[ 	]*$/d' $i
  17&nbsp;		# --&#62; Ditto, as above.
  18&nbsp;	done
  19&nbsp;fi
  20&nbsp;
  21&nbsp;# ==&#62; Exercise: Add error checking and other options.
  22&nbsp;# ==&#62;
  23&nbsp;# ==&#62; Note that the small sed script repeats, except for the arg passed.
  24&nbsp;# ==&#62; Does it make sense to embed it in a function? Why or why not?</PRE
></TD
></TR
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><HR></DIV
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="FTPGET"
></A
><P
><B
>Example A-13. <B
CLASS="COMMAND"
>ftpget</B
>: Downloading files via ftp
      </B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>   1&nbsp;#! /bin/sh 
   2&nbsp;# $Id: ftpget,v 1.2 91/05/07 21:15:43 moraes Exp $ 
   3&nbsp;# Script to perform batch anonymous ftp. Essentially converts a list of
   4&nbsp;# of command line arguments into input to ftp.
   5&nbsp;# ==&#62; This script is nothing but a shell wrapper around "ftp" . . .
   6&nbsp;# Simple, and quick - written as a companion to ftplist 
   7&nbsp;# -h specifies the remote host (default prep.ai.mit.edu) 
   8&nbsp;# -d specifies the remote directory to cd to - you can provide a sequence 
   9&nbsp;# of -d options - they will be cd'ed to in turn. If the paths are relative, 
  10&nbsp;# make sure you get the sequence right. Be careful with relative paths - 
  11&nbsp;# there are far too many symlinks nowadays.  
  12&nbsp;# (default is the ftp login directory)
  13&nbsp;# -v turns on the verbose option of ftp, and shows all responses from the 
  14&nbsp;# ftp server.  
  15&nbsp;# -f remotefile[:localfile] gets the remote file into localfile 
  16&nbsp;# -m pattern does an mget with the specified pattern. Remember to quote 
  17&nbsp;# shell characters.  
  18&nbsp;# -c does a local cd to the specified directory
  19&nbsp;# For example, 
  20&nbsp;# 	ftpget -h expo.lcs.mit.edu -d contrib -f xplaces.shar:xplaces.sh \
  21&nbsp;#		-d ../pub/R3/fixes -c ~/fixes -m 'fix*' 
  22&nbsp;# will get xplaces.shar from ~ftp/contrib on expo.lcs.mit.edu, and put it in
  23&nbsp;# xplaces.sh in the current working directory, and get all fixes from
  24&nbsp;# ~ftp/pub/R3/fixes and put them in the ~/fixes directory. 
  25&nbsp;# Obviously, the sequence of the options is important, since the equivalent
  26&nbsp;# commands are executed by ftp in corresponding order
  27&nbsp;#
  28&nbsp;# Mark Moraes &#60;[e-mail]&#62;, Feb 1, 1989 
  29&nbsp;#
  30&nbsp;
  31&nbsp;
  32&nbsp;# ==&#62; These comments added by author of this document.
  33&nbsp;
  34&nbsp;# PATH=/local/bin:/usr/ucb:/usr/bin:/bin
  35&nbsp;# export PATH
  36&nbsp;# ==&#62; Above 2 lines from original script probably superfluous.
  37&nbsp;
  38&nbsp;E_BADARGS=65
  39&nbsp;
  40&nbsp;TMPFILE=/tmp/ftp.$$
  41&nbsp;# ==&#62; Creates temp file, using process id of script ($$)
  42&nbsp;# ==&#62; to construct filename.
  43&nbsp;
  44&nbsp;SITE=`domainname`.toronto.edu
  45&nbsp;# ==&#62; 'domainname' similar to 'hostname'
  46&nbsp;# ==&#62; May rewrite this to parameterize this for general use.
  47&nbsp;
  48&nbsp;usage="Usage: $0 [-h remotehost] [-d remotedirectory]... [-f remfile:localfile]... \
  49&nbsp;		[-c localdirectory] [-m filepattern] [-v]"
  50&nbsp;ftpflags="-i -n"
  51&nbsp;verbflag=
  52&nbsp;set -f 		# So we can use globbing in -m
  53&nbsp;set x `getopt vh:d:c:m:f: $*`
  54&nbsp;if [ $? != 0 ]; then
  55&nbsp;	echo $usage
  56&nbsp;	exit $E_BADARGS
  57&nbsp;fi
  58&nbsp;shift
  59&nbsp;trap 'rm -f ${TMPFILE} ; exit' 0 1 2 3 15
  60&nbsp;# ==&#62; Delete tempfile in case of abnormal exit from script.
  61&nbsp;echo "user anonymous ${USER-gnu}@${SITE} &#62; ${TMPFILE}"
  62&nbsp;# ==&#62; Added quotes (recommended in complex echoes).
  63&nbsp;echo binary &#62;&#62; ${TMPFILE}
  64&nbsp;for i in $*   # ==&#62; Parse command line args.
  65&nbsp;do
  66&nbsp;	case $i in
  67&nbsp;	-v) verbflag=-v; echo hash &#62;&#62; ${TMPFILE}; shift;;
  68&nbsp;	-h) remhost=$2; shift 2;;
  69&nbsp;	-d) echo cd $2 &#62;&#62; ${TMPFILE}; 
  70&nbsp;	    if [ x${verbflag} != x ]; then
  71&nbsp;	        echo pwd &#62;&#62; ${TMPFILE};
  72&nbsp;	    fi;
  73&nbsp;	    shift 2;;
  74&nbsp;	-c) echo lcd $2 &#62;&#62; ${TMPFILE}; shift 2;;
  75&nbsp;	-m) echo mget "$2" &#62;&#62; ${TMPFILE}; shift 2;;
  76&nbsp;	-f) f1=`expr "$2" : "\([^:]*\).*"`; f2=`expr "$2" : "[^:]*:\(.*\)"`;
  77&nbsp;	    echo get ${f1} ${f2} &#62;&#62; ${TMPFILE}; shift 2;;
  78&nbsp;	--) shift; break;;
  79&nbsp;	esac
  80&nbsp;        # ==&#62; 'lcd' and 'mget' are ftp commands. See "man ftp" . . .
  81&nbsp;done
  82&nbsp;if [ $# -ne 0 ]; then
  83&nbsp;	echo $usage
  84&nbsp;	exit $E_BADARGS
  85&nbsp;        # ==&#62; Changed from "exit 2" to conform with style standard.
  86&nbsp;fi
  87&nbsp;if [ x${verbflag} != x ]; then
  88&nbsp;	ftpflags="${ftpflags} -v"
  89&nbsp;fi
  90&nbsp;if [ x${remhost} = x ]; then
  91&nbsp;	remhost=prep.ai.mit.edu
  92&nbsp;	# ==&#62; Change to match appropriate ftp site.
  93&nbsp;fi
  94&nbsp;echo quit &#62;&#62; ${TMPFILE}
  95&nbsp;# ==&#62; All commands saved in tempfile.
  96&nbsp;
  97&nbsp;ftp ${ftpflags} ${remhost} &#60; ${TMPFILE}
  98&nbsp;# ==&#62; Now, tempfile batch processed by ftp.
  99&nbsp;
 100&nbsp;rm -f ${TMPFILE}
 101&nbsp;# ==&#62; Finally, tempfile deleted (you may wish to copy it to a logfile).
 102&nbsp;
 103&nbsp;
 104&nbsp;# ==&#62; Exercises:
 105&nbsp;# ==&#62; ---------
 106&nbsp;# ==&#62; 1) Add error checking.
 107&nbsp;# ==&#62; 2) Add bells &#38; whistles.</PRE
></TD
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><HR></DIV
><P
>+</P
><P
>Antek Sawicki contributed the following script, which makes very
      clever use of the parameter substitution operators discussed in
      <A
HREF="parameter-substitution.html"
>Section 9.3</A
>.</P
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="PW"
></A
><P
><B
>Example A-14. <B
CLASS="COMMAND"
>password</B
>: Generating random
      8-character passwords</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>   1&nbsp;#!/bin/bash
   2&nbsp;# May need to be invoked with  #!/bin/bash2  on older machines.
   3&nbsp;#
   4&nbsp;# Random password generator for Bash 2.x by Antek Sawicki &#60;[e-mail]&#62;,
   5&nbsp;# who generously gave permission to the document author to use it here.
   6&nbsp;#
   7&nbsp;# ==&#62; Comments added by document author ==&#62;
   8&nbsp;
   9&nbsp;
  10&nbsp;MATRIX="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
  11&nbsp;# ==&#62; Password will consist of alphanumeric characters.
  12&nbsp;LENGTH="8"
  13&nbsp;# ==&#62; May change 'LENGTH' for longer password.
  14&nbsp;
  15&nbsp;
  16&nbsp;while [ "${n:=1}" -le "$LENGTH" ]
  17&nbsp;# ==&#62; Recall that := is "default substitution" operator.
  18&nbsp;# ==&#62; So, if 'n' has not been initialized, set it to 1.
  19&nbsp;do
  20&nbsp;	PASS="$PASS${MATRIX:$(($RANDOM%${#MATRIX})):1}"
  21&nbsp;	# ==&#62; Very clever, but tricky.
  22&nbsp;
  23&nbsp;	# ==&#62; Starting from the innermost nesting...
  24&nbsp;	# ==&#62; ${#MATRIX} returns length of array MATRIX.
  25&nbsp;
  26&nbsp;	# ==&#62; $RANDOM%${#MATRIX} returns random number between 1
  27&nbsp;	# ==&#62; and [length of MATRIX] - 1.
  28&nbsp;
  29&nbsp;	# ==&#62; ${MATRIX:$(($RANDOM%${#MATRIX})):1}
  30&nbsp;	# ==&#62; returns expansion of MATRIX at random position, by length 1. 
  31&nbsp;	# ==&#62; See {var:pos:len} parameter substitution in Chapter 9.
  32&nbsp;	# ==&#62; and the associated examples.
  33&nbsp;
  34&nbsp;	# ==&#62; PASS=... simply pastes this result onto previous PASS (concatenation).
  35&nbsp;
  36&nbsp;	# ==&#62; To visualize this more clearly, uncomment the following line
  37&nbsp;	#                 echo "$PASS"
  38&nbsp;	# ==&#62; to see PASS being built up,
  39&nbsp;	# ==&#62; one character at a time, each iteration of the loop.
  40&nbsp;
  41&nbsp;	let n+=1
  42&nbsp;	# ==&#62; Increment 'n' for next pass.
  43&nbsp;done
  44&nbsp;
  45&nbsp;echo "$PASS"      # ==&#62; Or, redirect to a file, as desired.
  46&nbsp;
  47&nbsp;exit 0</PRE
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><HR></DIV
><P
>+</P
><P
><A
NAME="ZFIFO"
></A
>James R. Van Zandt contributed this script,
      which uses named pipes and, in his words, <SPAN
CLASS="QUOTE"
>"really exercises
      quoting and escaping"</SPAN
>.</P
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="FIFO"
></A
><P