eval如何使用?

引用:

-(dearvoid@LinuxEden:Forum)-(~/void/bash)-
[$$=17253 $?=0] ; cat colorize.sh
#!/bin/bash
#
# Author: Clark J. Wang <dearvoid at gmail.com>
#
#--------------------------------------------------------------------#
#
# Usage: colorize [-n] COLOR TEXT
#
# If -n is specified, the trailing newline is suppressed.
#
function colorize()
{
    local bNewLine=1 sNewLineOpt
    local sClr aValidClrs bValidClr=0
    local sClrName sText

    local default=$'\033[0m'
    local   black=$'\033[0;30m'
    local    Gray=$'\033[1;30m'
    local     red=$'\033[0;31m'
    local     Red=$'\033[1;31m'
    local   green=$'\033[0;32m'
    local   Green=$'\033[1;32m'
    local   brown=$'\033[0;33m'
    local  yellow=$'\033[1;33m'
    local    blue=$'\033[0;34m'
    local    Blue=$'\033[1;34m'
    local  purple=$'\033[0;35m'
    local  Purple=$'\033[1;35m'
    local    cyan=$'\033[0;36m'
    local    Cyan=$'\033[1;36m'
    local    gray=$'\033[0;37m'
    local   white=$'\033[1;37m'

    aValidClrs=(black white red Red green Green brown yellow blue Blue \
                purple Purple cyan Cyan gray Gray default)

    if [ $# = 3 ]; then
        if [ "$1" = '-n' ]; then
            bNewLine=0
            sNewLineOpt='-n'
        else
            echo "Error: usage error" 1>&2
            return 1
        fi

        shift
    elif [ $# != 2 ]; then
        echo "Error: usage error" 1>&2
        return 1
    fi
    sClrName=$1
    sText=$2

    for sClr in ${aValidClrs[@]}; do
        if [ "$sClr" = "$sClrName" ]; then
            bValidClr=1
        fi
    done

    if ((bValidClr)); then
        eval "echo $sNewLineOpt \"\$$sClrName\$sText\$default\""
    else
        echo "Error: invalid color name \`$sClrName'" 1>&2
        return 1
    fi
}

#-- main ------------------------------------------------------------#

colorize "$@"
-(dearvoid@LinuxEden:Forum)-(~/void/bash)-
[$$=17253 $?=0] ; ./colorize.sh red 'This is red'
This is red
-(dearvoid@LinuxEden:Forum)-(~/void/bash)-
[$$=17253 $?=0] ; ./colorize.sh purple 'This is purple'
This is purple
-(dearvoid@LinuxEden:Forum)-(~/void/bash)-
[$$=17253 $?=0] ; bye

复制内容到剪贴板

代码:

unamer=$(uname -r)
version=$(echo $unamer | awk -F '.' '{ print "(" $1 " " $2 ")" }')
echo $version
unamer=$(uname -r)
eval version=$(echo $unamer | awk -F '.' '{ print "(" $1 " " $2 ")" }')
echo ${version［＊］}

复制内容到剪贴板

代码:

unamer=$(uname -r)
version=$(echo $unamer | awk -F '.' '{ print "(" $1 " " $2 ")" }')
echo ${#version}
unamer=$(uname -r)
eval version=$(echo $unamer | awk -F '.' '{ print "(" $1 " " $2 ")" }')
echo ${version[*]}

引用:

eval version=$(echo $unamer | awk -F '.' '{ print "(" $1 " " $2 ")" }')