contributed-scripts.html

Shall高级编程

 249 
 250 
 251   if [ ${array[$cell_number]} = "$ALIVE1" ]
 252   then
 253     let "count -= 1"        #  Make sure value of tested cell itself
 254   fi                        #+ is not counted.
 255 
 256 
 257   return $count
 258   
 259 }
 260 
 261 next_gen ()               # Update generation array.
 262 {
 263 
 264 local array
 265 local i=0
 266 
 267 array=( `echo "$1"` )     # Convert passed arg to array.
 268 
 269 while [ "$i" -lt "$cells" ]
 270 do
 271   IsAlive "$1" $i ${array[$i]}   # Is cell alive?
 272   if [ $? -eq "$ALIVE" ]
 273   then                           #  If alive, then
 274     array[$i]=.                  #+ represent the cell as a period.
 275   else  
 276     array[$i]="_"                #  Otherwise underscore
 277    fi                            #+ (which will later be converted to space).  
 278   let "i += 1" 
 279 done   
 280 
 281 
 282 # let "generation += 1"   # Increment generation count.
 283 # Why was the above line commented out?
 284 
 285 
 286 # Set variable to pass as parameter to "display" function.
 287 avar=`echo ${array[@]}`   # Convert array back to string variable.
 288 display "$avar"           # Display it.
 289 echo; echo
 290 echo "Generation $generation  -  $alive alive"
 291 
 292 if [ "$alive" -eq 0 ]
 293 then
 294   echo
 295   echo "Premature exit: no more cells alive!"
 296   exit $NONE_ALIVE        #  No point in continuing
 297 fi                        #+ if no live cells.
 298 
 299 }
 300 
 301 
 302 # =========================================================
 303 
 304 # main ()
 305 
 306 # Load initial array with contents of startup file.
 307 initial=( `cat "$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
></TD
></TR
></TABLE
><HR></DIV
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="GEN0DATA"
></A
><P
><B
>Example A-11. Data file for <I
CLASS="FIRSTTERM"
>Game of Life</I
></B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>   1&nbsp;# gen0
   2&nbsp;#
   3&nbsp;# This is an example "generation 0" start-up file for "life.sh".
   4&nbsp;# --------------------------------------------------------------
   5&nbsp;#  The "gen0" file is a 10 x 10 grid using a period (.) for live cells,
   6&nbsp;#+ and an underscore (_) for dead ones. We cannot simply use spaces
   7&nbsp;#+ for dead cells in this file because of a peculiarity in Bash arrays.
   8&nbsp;#  [Exercise for the reader: explain this.]
   9&nbsp;#
  10&nbsp;# Lines beginning with a '#' are comments, and the script ignores them.
  11&nbsp;__.__..___
  12&nbsp;___._.____
  13&nbsp;____.___..
  14&nbsp;_._______.
  15&nbsp;____._____
  16&nbsp;..__...___
  17&nbsp;____._____
  18&nbsp;___...____
  19&nbsp;__.._..___
  20&nbsp;_..___..__</PRE
></TD
></TR
></TABLE
><HR></DIV
><P
>+++</P
><P
>The following two scripts are by Mark Moraes of the University
    of Toronto. See the file <TT
CLASS="FILENAME"
>Moraes-COPYRIGHT</TT
>
    for permissions and restrictions. This file is included in the
    combined <A
HREF="index.html#WHERE_TARBALL"
>HTML/source tarball</A
>
    of the <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>ABS Guide</I
></SPAN
>.</P
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="BEHEAD"
></A
><P
><B
>Example A-12. <I
CLASS="FIRSTTERM"
>behead</I
>: 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
></TABLE
><HR></DIV
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="FTPGET"
></A
><P
><B
>Example A-13. <I
CLASS="FIRSTTERM"
>ftpget</I
>: 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
  23&nbsp;# in 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]... \ 
  49&nbsp;[-f remfile:localfile]...  [-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;                   Signals:   HUP   INT (Ctl-C)    QUIT     TERM
  61&nbsp;# ==&#62; Delete tempfile in case of abnormal exit from script.
  62&nbsp;echo "user anonymous ${USER-gnu}@${SITE} &#62; ${TMPFILE}"
  63&nbsp;# ==&#62; Added quotes (recommended in complex echoes).
  64&nbsp;echo binary &#62;&#62; ${TMPFILE}
  65&nbsp;for i in $*   # ==&#62; Parse command line args.
  66&nbsp;do
  67&nbsp;	case $i in
  68&nbsp;	-v) verbflag=-v; echo hash &#62;&#62; ${TMPFILE}; shift;;
  69&nbsp;	-h) remhost=$2; shift 2;;
  70&nbsp;	-d) echo cd $2 &#62;&#62; ${TMPFILE}; 
  71&nbsp;	    if [ x${verbflag} != x ]; then
  72&nbsp;	        echo pwd &#62;&#62; ${TMPFILE};
  73&nbsp;	    fi;
  74&nbsp;	    shift 2;;
  75&nbsp;	-c) echo lcd $2 &#62;&#62; ${TMPFILE}; shift 2;;
  76&nbsp;	-m) echo mget "$2" &#62;&#62; ${TMPFILE}; shift 2;;
  77&nbsp;	-f) f1=`expr "$2" : "\([^:]*\).*"`; f2=`expr "$2" : "[^:]*:\(.*\)"`;
  78&nbsp;	    echo get ${f1} ${f2} &#62;&#62; ${TMPFILE}; shift 2;;
  79&nbsp;	--) shift; break;;
  80&nbsp;	esac
  81&nbsp;        # ==&#62; 'lcd' and 'mget' are ftp commands. See "man ftp" . . .
  82&nbsp;done
  83&nbsp;if [ $# -ne 0 ]; then
  84&nbsp;	echo $usage
  85&nbsp;	exit $E_BADARGS
  86&nbsp;        # ==&#62; Changed from "exit 2" to conform with style standard.
  87&nbsp;fi
  88&nbsp;if [ x${verbflag} != x ]; then
  89&nbsp;	ftpflags="${ftpflags} -v"
  90&nbsp;fi
  91&nbsp;if [ x${remhost} = x ]; then
  92&nbsp;	remhost=prep.ai.mit.edu
  93&nbsp;	# ==&#62; Change to match appropriate ftp site.
  94&nbsp;fi
  95&nbsp;echo quit &#62;&#62; ${TMPFILE}
  96&nbsp;# ==&#62; All commands saved in tempfile.
  97&nbsp;
  98&nbsp;ftp ${ftpflags} ${remhost} &#60; ${TMPFILE}
  99&nbsp;# ==&#62; Now, tempfile batch processed by ftp.
 100&nbsp;
 101&nbsp;rm -f ${TMPFILE}
 102&nbsp;# ==&#62; Finally, tempfile deleted (you may wish to copy it to a logfile).
 103&nbsp;
 104&nbsp;
 105&nbsp;# ==&#62; Exercises:
 106&nbsp;# ==&#62; ---------
 107&nbsp;# ==&#62; 1) Add error checking.
 108&nbsp;# ==&#62; 2) Add bells &#38; whistles.</PRE
></TD
></TR
></TABLE
><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
><P
><A
NAME="PW0"
></A
></P
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="PW"
></A
><P
><B
>Example A-14. <I
CLASS="FIRSTTERM"
>password</I
>: 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 +
   5&nbsp;#+ by Antek Sawicki &#60;[e-mail]&#62;,
   6&nbsp;#+ who generously gave usage permission to the ABS Guide author.
   7&nbsp;#
   8&nbsp;# ==&#62; Comments added by document author ==&#62;