May 22, 2021 Linux
The test command in the shell is used to check that a condition is true and that it can be tested in three areas: numeric, character, and file.
| Parameters | Description |
|---|---|
| -eq | Equal to true |
| -ne | Not equal to true |
| -gt | Greater than is true |
| -ge | If it is greater than or equal to true |
| -lt | Less than is true |
| -le | Less than or equal to true |
Example demonstration:
num1=100 num2=100 if test $[num1] -eq $[num2] then echo '两个数相等！' else echo '两个数不相等！' fi
Output:
两个数相等！
| Parameters | Description |
|---|---|
| = | Equal to true |
| != | It's true if you're not equal |
| -z string | A string length of zero is true |
| -n string | If the string length is not zero, it is true |
Example demonstration:
num1="W3Cschool" num2="W3Cschool" if test num1=num2 then echo '两个字符串相等!' else echo '两个字符串不相等!' fi
Output:
两个字符串相等!
| Parameters | Description |
|---|---|
| -e File name | True if the file exists |
| -r file name | True if the file exists and is readable |
| -w file name | True if the file exists and can be written |
| -x file name | True if the file exists and can be executed |
| -s file name | True if the file exists and has at least one character |
| -d File name | True if the file exists and is a directory |
| -f File name | True if the file exists and is normal |
| -c File name | True if the file exists and is character-specific |
| -b File name | True if the file exists and is a special block file |
Example demonstration:
cd /bin if test -e ./bash then echo '文件已存在!' else echo '文件不存在!' fi
Output:
文件已存在!
In addition, shell also provides with ( -a), or (-o), non- ( ! T hree logical operators are used to connect test conditions with the priority:!" H ighest, "-a" second, "-o" lowest. For example:
cd /bin if test -e ./notFile -o -e ./bash then echo '有一个文件存在!' else echo '两个文件都不存在' fi
Output:
有一个文件存在!