用来检测输入的选项$1是否在PATH中的shell脚本_linux shell_

 #!/bin/sh # inpath - Verifies that a specified program is either valid as is, # or that it can be found in the PATH directory list. in_path() { # Given a command and the PATH, try to find the command. Returns # 0 if found and executable, 1 if not. Note that this temporarily modifies # the IFS (input field separator) but restores it upon completion. cmd=$1 path=$2 retval=1 oldIFS=$IFS IFS=":" for directory in $path do if [ -x $directory/$cmd ] ; then retval=0 # if we're here, we found $cmd in $directory fi done IFS=$oldIFS return $retval } checkForCmdInPath() { var=$1 # The variable slicing notation in the following conditional # needs some explanation: ${var#expr} returns everything after # the match for 'expr' in the variable value (if any), and # ${var%expr} returns everything that doesn't match (in this # case, just the very first character. You can also do this in # Bash with ${var:0:1}, and you could use cut too: cut -c1. if [ "$var" != "" ] ; then if [ "${var%${var#?}}" = "/" ] ; then if [ ! -x $var ] ; then return 1 fi elif ! in_path $var $PATH ; then return 2 fi fi } if [ $# -ne 1 ] ; then echo "Usage: $0 command" >&2 ; exit 1 fi checkForCmdInPath "$1" case $? in 0 ) echo "$1 found in PATH" ;; 1 ) echo "$1 not found or not executable" ;; 2 ) echo "$1 not found in PATH" ;; esac exit 0