Many things can be tested for natively in Bash, without the need to make fancy if statements. More information can be found by running "man test" but here are the most interesting ones:
- File Existance
[ -f filename ]
- File is a link
[ -L filename ] OR [ -h filename ] (Both are equivalent)
- Variable is not empty
[ -n var ]
- File is not empty
[ -s filename ]
- Greater Than
[ var1 -gt var2 ]
- Greater or equal
-
[ var1 -ge var2 ]
- Integer Equality
[ int1 -eq int2 ]
- Lower Than
[ var1 -lt var2 ]
- Lower or equal
-
[ var1 -le var2 ]
- Non-null string
[ -z var]
- String Equality
[ str1 = str2 ] (Can also use [ str1 == str2 ], with slightly different implications)
For testing two different things, you can use:
&&- With the meaning of "and", to check that both are true
||- With the meaning of "or", to check if either of the conditions are true
