Bash将命令输出与字符串进行比较[重复]

Question

输出是一样的，它总是回显need to pull。 如果我在if 条件中删除$text 周围的引号，则会引发too many arguments 错误。

var="$(git status -uno)" && 

text="On branch master Your branch is up-to-date with 'origin/master'. nothing to commit (use -u to show untracked files)"; 

echo  $var; 
echo  $text; 
if [ "$var" = "$text" ]; then
    echo "Up-to-date"
else
    echo "need to pull"
fi

Answer 1

最好这样做，=~ 用于 bash 正则表达式：

#!/bin/bash

var="$(git status -uno)" 

if [[ $var =~ "nothing to commit" ]]; then
    echo "Up-to-date"
else
    echo "need to pull"
fi

或

#!/bin/bash

var="$(git status -uno)" 

if [[ $var == *nothing\ to\ commit* ]]; then
    echo "Up-to-date"
else
    echo "need to pull"
fi

Answer 2

警告：bash 的正则表达式需要更多资源，在其他shell 中不起作用！

简单的旧时尚

此语法与 POSIX 兼容，仅与 bash 不兼容！

if LANG=C git status -uno | grep -q up-to-date ; then
    echo "Nothing to do"
else
    echo "Need to upgrade"
fi

或者测试一个变量（posix 也是）

来自this answer to How to check if a string contains a substring in Bash，这是一个兼容的语法，在any 标准POSIX shell下工作：

#!/bin/sh

stringContain() { [ -z "${2##*$1*}" ] && { [ -z "$1" ] || [ -n "$2" ] ;} ; }

var=$(git status -uno)

if  stringContain "up-to-date" "$var" ;then
    echo "Up-to-date"
    # Don't do anything
else
    echo "need to pull"
    # Ask for upgrade, see: 
fi