Shell 命令詳解之 if 命令
阿新 • • 發佈:2018-12-01
Shell 命令詳解之 if
命令
1. 常用引數
-eq
:等於[equal]
-n
: 字串是否不為空
-ne
:不等於[not equal]
-le
:小於等於[less and equal]
-ge
:大於等於[greater and equal]
-lt
:小於[less than]
-gt
:大於[greater than]
-a
: 與 [and]
-o
:或 [or]
!
:非
- example 1
-eq
指令碼如下:
[[email protected] shells]# cat test1.sh
#!/bin/bash
a=$1
if [ $a -eq 1 ]
then
echo a = 1
else
echo a != 1
fi
執行結果:
[[email protected] shells]# ./test1.sh 1
a = 1
[[email protected]erver4 shells]# ./test1.sh 2
a != 1
- example 2
-n
[[email protected] shells]# cat test1.sh
#!/bin/bash
a=$1
if [ -n "$a" ];
then
echo a isn"'"t empty string
else
echo a is empty string
fi
[[email protected] shells]# ./test1.sh
a is empty string
[[email protected] shells]# ./test1.sh hadoop
a isn't empty string