bash 检查命令的输出是否包含 shell 脚本中的某个字符串
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Checking if output of a command contains a certain string in a shell script
提问by user1118764
I'm writing a shell script, and I'm trying to check if the output of a command contains a certain string. I'm thinking I probably have to use grep, but I'm not sure how. Does anyone know?
我正在编写一个 shell 脚本，我正在尝试检查命令的输出是否包含某个字符串。我想我可能必须使用 grep，但我不确定如何使用。有人知道吗？
采纳答案by perreal
Test the return value of grep:
测试grep的返回值：
./somecommand | grep 'string' &> /dev/null
if [ $? == 0 ]; then
echo "matched"
fi
which is done idiomatically like so:
这是惯用的方式：
if ./somecommand | grep -q 'string'; then
echo "matched"
fi
and also:
并且：
./somecommand | grep -q 'string' && echo 'matched'
回答by mat
Testing $?is an anti-pattern
测试$?是一种反模式
if ./somecommand |?grep -q 'string'; then
echo "matched"
fi
回答by Noam Manos
Another option is to check for regular expression match on the command output.
另一种选择是检查命令输出上的正则表达式匹配。
For example:
例如：
[[ "$(./somecommand)" =~ "sub string" ]] && echo "Output includes 'sub string'"
回答by Ehsan Barkhordar
A clean if/else conditional shell script:
一个干净的 if/else 条件 shell 脚本：
if ./somecommand | grep -q 'some_string'; then
echo "exists"
else
echo "doesn't exist"
fi
