if

if else

Note

下面 == 两边的比较内容与[]中括号之间要有空格，如果没空格会报错。

[alvin@poppy ~]$ cat if.sh
#!/bin/bash

name='alvin'
if [ $name == 'alvin' ];then
    echo 'nice alvin'
else
    echo 'no alvin'
fi
[alvin@poppy ~]$ ./if.sh
nice alvin

if elif

[alvin@poppy ~]$ cat if.sh
#!/bin/bash

#name='alvin'
name='ophira'
if [ $name == 'alvin' ];then
    echo 'nice alvin'
elif [ $name == 'ophira' ];then
    echo 'ophira'
else
    echo 'no alvin'
fi
[alvin@poppy ~]$ ./if.sh
ophira