contributed-scripts.html

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306 # Load initial array with contents of startup file.
307 initial=( `cat "$startfile" | sed -e '/#/d' | tr -d '\n' |\
308 sed -e 's/\./\. /g' -e 's/_/_ /g'` )
309 # Delete lines containing '#' comment character.
310 # Remove linefeeds and insert space between elements.
311 
312 clear          # Clear screen.
313 
314 echo #         Title
315 echo "======================="
316 echo "    $GENERATIONS generations"
317 echo "           of"
318 echo "\"Life in the Slow Lane\""
319 echo "======================="
320 
321 
322 # -------- Display first generation. --------
323 Gen0=`echo ${initial[@]}`
324 display "$Gen0"           # Display only.
325 echo; echo
326 echo "Generation $generation  -  $alive alive"
327 # -------------------------------------------
328 
329 
330 let "generation += 1"     # Increment generation count.
331 echo
332 
333 # ------- Display second generation. -------
334 Cur=`echo ${initial[@]}`
335 next_gen "$Cur"          # Update & display.
336 # ------------------------------------------
337 
338 let "generation += 1"     # Increment generation count.
339 
340 # ------ Main loop for displaying subsequent generations ------
341 while [ "$generation" -le "$GENERATIONS" ]
342 do
343   Cur="$avar"
344   next_gen "$Cur"
345   let "generation += 1"
346 done
347 # ==============================================================
348 
349 echo
350 
351 exit 0   # END
352 
353 
354 
355 # The grid in this script has a "boundary problem."
356 # The the top, bottom, and sides border on a void of dead cells.
357 # Exercise: Change the script to have the grid wrap around,
358 # +         so that the left and right sides will "touch,"      
359 # +         as will the top and bottom.
360 #
361 # Exercise: Create a new "gen0" file to seed this script.
362 #           Use a 12 x 16 grid, instead of the original 10 x 10 one.
363 #           Make the necessary changes to the script,
364 #+          so it will run with the altered file.
365 #
366 # Exercise: Modify this script so that it can determine the grid size
367 #+          from the "gen0" file, and set any variables necessary
368 #+          for the script to run.
369 #           This would make unnecessary any changes to variables
370&nbsp;#+          in the script for an altered grid size.</PRE
></FONT
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><HR></DIV
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="GEN0DATA"
></A
><P
><B
>例子 A-11. <SPAN
CLASS="QUOTE"
>"Game of Life"</SPAN
>的数据文件</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><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
>下面的两个脚本是由多伦多大学的Mark Moraes编写的. 
    请参考附件文件<SPAN
CLASS="QUOTE"
>"Moraes-COPYRIGHT"</SPAN
>, 
    详细的指明了授权与约定. </P
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="BEHEAD"
></A
><P
><B
>例子 A-12. <B
CLASS="COMMAND"
>behead</B
>: 去掉信件与新消息的头</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><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
></FONT
></TD
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><HR></DIV
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="FTPGET"
></A
><P
><B
>例子 A-13. <B
CLASS="COMMAND"
>ftpget</B
>: 通过ftp下载文件</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><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 ${TMPFILE}
101&nbsp;# ==&#62; Finally, tempfile deleted (you may wish to copy it to a logfile).
102&nbsp;
103&nbsp;
104&nbsp;# ==&#62; Exercises:
105&nbsp;# ==&#62; ---------
106&nbsp;# ==&#62; 1) Add error checking.
107&nbsp;# ==&#62; 2) Add bells &#38; whistles.</PRE
></FONT
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><HR></DIV
><P
>+</P
><P
>Antek Sawicki捐献了下面的脚本, 这个脚本非常聪明的使用了参数替换操作符, 
		我们在<A
HREF="parameter-substitution.html"
>Section 9.3</A
>中讨论了参数替换操作符. </P
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="PW"
></A
><P
><B
>例子 A-14. <B
CLASS="COMMAND"
>password</B
>: 产生随机的8个字符的密码</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><PRE
CLASS="PROGRAMLISTING"
>  1&nbsp;#!/bin/bash
  2&nbsp;# May need to be invoked with  #!/bin/bash2  on older machines.
  3&nbsp;#
  4&nbsp;# Random password generator for Bash 2.x by Antek Sawicki &#60;[e-mail]&#62;,
  5&nbsp;# who generously gave permission to the document author to use it here.
  6&nbsp;#
  7&nbsp;# ==&#62; Comments added by document author ==&#62;
  8&nbsp;
  9&nbsp;
 10&nbsp;MATRIX="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
 11&nbsp;# ==&#62; Password will consist of alphanumeric characters.
 12&nbsp;LENGTH="8"
 13&nbsp;# ==&#62; May change 'LENGTH' for longer password.
 14&nbsp;
 15&nbsp;
 16&nbsp;while [ "${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
></FONT
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><HR></DIV
><P
>+</P
><P
><A
NAME="ZFIFO"
></A
>James R. Van Zandt捐献了这个脚本, 
      使用命名管道, 用他的话来说, <SPAN
CLASS="QUOTE"
>"引用与转义的真正练习"</SPAN
>. </P
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="FIFO"
></A
><P
><B
>例子 A-15. <B
CLASS="COMMAND"
>fifo</B
>: 使用命名管道来做每日的备份</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><PRE
CLASS="PROGRAMLISTING"
>  1&nbsp;#!/bin/bash
  2&nbsp;# ==&#62; Script by James R. Van Zandt, and used here with his permission.
  3&nbsp;
  4&nbsp;# ==&#62; Comments added by author of this document.
  5&nbsp;