Shell 命令返回值判断
文章目录
1.判断命令是否存在
1.1 优雅方法1
首先，检查命令是否有效的惯用方法直接在if语句中。
if command; then echo notify user OK >&2 else echo notify user FAIL >&2 return -1 fi
（良好做法：使用>&2将消息发送给stderr。）
1.2 优雅方法2
将通用逻辑转移到共享函数中。
check() { local command=("$@") if "${command[@]}"; then echo notify user OK >&2 else echo notify user FAIL >&2 exit 1 fi } check command1 check command2 check command3
1.3 优雅方法3
installed () { command -v "$1" >/dev/null 2>&1 } if installed <command1> then <command1> xx else <command1> xxx fi
2. 返回错误退出
2.1 || exit 退出
command1 || exit command2 || exit command3 || exit
2.2 bash -e
$ bash -e xx.sh #!/bin/bash -e xx.sh command1 command2 command3
2.3 set -e
$ bash xx.sh #!/bin/bash set -e command1 command2 command3
3. 返回错误提示
3.1 一般方法
方法1
if do some command; then echo notify user OK else echo notify user fail exit 255 # exit code must be unsigned short fi
方法2
do some command if [ $? -eq 0 ]; then echo notify user OK else echo notify user FAIL return -1 fi
3.2 优雅方法
方法1
die() { local message=$1 echo "$message" >&2 exit 1 } command1 || die 'command1 failed' command2 || die 'command2 failed' command3 || die 'command3 failed'
方法2（推荐）
warn () { echo "$@" >&2 } die () { status="$1" shift warn "$@" exit "$status" } do some command && echo notify user OK || die 255 Notify user fail
