String tests (GNU Coreutils 9.0)
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16.3.4 String tests
These options test string characteristics. You may need to quote string arguments for the shell. For example:
test -n "$V"
The quotes here prevent the wrong arguments from being passed to test if ‘$V’ is empty or contains special characters.
- ‘
-z string’ True if the length of
stringis zero.- ‘
-n string’
‘string’ True if the length of
stringis nonzero.- ‘
string1 = string2’ True if the strings are equal.
- ‘
string1 == string2’ True if the strings are equal (synonym for =). Note this form is not as portable to other shells and systems.
- ‘
string1 != string2’ True if the strings are not equal.
