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標(biāo)題: 100 CoolShell ch01 問(wèn)題 [打印本頁(yè)]
作者: yanjerry9133    時(shí)間: 2012-03-20 16:53
標(biāo)題: 100 CoolShell ch01 問(wèn)題
  1. #!/bin/sh
  2. # inpath - Verifies that a specified program is either valid as is,
  3. #   or that it can be found in the PATH directory list.

  5. in_path()
  6. {
  7.   # Given a command and the PATH, try to find the command. Returns
  8.   # 0 if found and executable, 1 if not. Note that this temporarily modifies
  9.   # the IFS (input field separator) but restores it upon completion.

  11.   cmd=$1        path=$2         retval=1
  12.   oldIFS=$IFS   IFS=":"

  14.   for directory in $path
  15.   do
  16.     if [ -x $directory/$cmd ] ; then
  17.       retval=0      # if we're here, we found $cmd in $directory
  18.     fi
  19.   done
  20.   IFS=$oldIFS
  21.   return $retval
  22. }

  24. checkForCmdInPath()
  25. {
  26.   var=$1

  28.   # The variable slicing notation in the following conditional
  29.   # needs some explanation: ${var#expr} returns everything after
  30.   # the match for 'expr' in the variable value (if any), and
  31.   # ${var%expr} returns everything that doesn't match (in this
  32.   # case, just the very first character. You can also do this in
  33.   # Bash with ${var:0:1}, and you could use cut too: cut -c1.

  35.   if [ "$var" != "" ] ; then
  36.     if [ "${var%${var#?}}" = "/" ] ; then
  37.       if [ ! -x $var ] ; then
  38.         return 1
  39.       fi
  40.     elif ! in_path $var $PATH ; then
  41.       return 2
  42.     fi
  43.   fi
  44. }

復(fù)制代碼
其中后那個(gè)elif ! in_path $var $PATH 看不懂啊，請(qǐng)教各位。。。
作者: Shell_HAT    時(shí)間: 2012-03-20 18:40
調(diào)用函數(shù)in_path，$var和$PATH傳到函數(shù)里面之后就是$1和$2
還有哪里不懂？



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