字符串相等比较

相等：在[]中使用==或=

[root@master Workspace]# ./test.sh 
true
[root@master Workspace]# cat test.sh 
#! /bin/sh

a="test"

if [ "$a" = "test" ];then
    echo "true"
fi
# or
[root@master Workspace]# ./test.sh 
true
[root@master Workspace]# cat test.sh 
#! /bin/sh

a="test"

if [ "$a" == "test" ];then
    echo "true"
fi

不等：在[]中使用!=

[root@master Workspace]# cat test.sh 
#! /bin/sh

a="test"

if [ "$a" != "test" ];then
    echo "true"
fi
[root@master Workspace]# ./test.sh 

字符串包含

在[[ ]]中使用=~

[root@master Workspace]# ./test.sh 
true
[root@master Workspace]# cat test.sh 
#! /bin/sh

a="test"

if [[ "$a" =~ "es" ]];then
    echo "true"
fi

不包含

[root@master Workspace]# cat test.sh 
#! /bin/sh

a="test"

if [[ ! "$a" =~ "es" ]];then
    echo "true"
fi

模式匹配

[root@master Workspace]# cat test.sh 
#! /bin/sh

a="test"
# 以t开头
if [[  "$a" == t* ]];then
    echo "true"
fi
[root@master Workspace]# ./test.sh 
true

shell脚本#为注释符号，那么如何判断以#开头呢？

[root@master Workspace]# ./test.sh 
true
[root@master Workspace]# cat test.sh 
#! /bin/sh

a="#test"

if [[  "$a" == ''#*'' ]];then
    echo "true"
fi
# or 
[root@master Workspace]# ./test.sh 
true
[root@master Workspace]# cat test.sh 
#! /bin/sh

a="#test"

if [[  "$a" == \#* ]];then
    echo "true"
fi