[Appendix B] B.4 Test Operators

B.4 Test Operators

These are the operators that are used with the [[ ... ]] construct. They can be logically combined with && ("and") and || ("or") and grouped with parenthesis.

Operator	True If...
-a file	file exists.
-b file	file is a block device file.
-c file	file is a character device file.
-d file	file is a directory.
-f file	file is a regular file.
-g file	file has its setgid bit set.
-k file	file has its sticky bit set.
-n string	string is non-null.
-o option	option is set.
-p file	file is a pipe or named pipe (FIFO file).
-r file	file is readable.
-s file	file is not empty.
-t N	File descriptor N points to a terminal.
-u file	file has its setuid bit set.
-w file	file is writeable.
-x file	file is executable, or file is a directory that can be searched.
-z string	string is null.
-G file	file 's group ID is the same as that of the shell.
-L file	file is a symbolic link.
-O file	file is owned by the shell's user ID.
-S file	file is a socket.
fileA -nt fileB	fileA is newer than fileB .
fileA -ot fileB	fileA is older than fileB .
fileA -ef fileB	fileA and fileB point to the same file.
string = pattern	string matches pattern (which can contain wildcards).
string != pattern	string does not match pattern .
stringA < stringB	stringA comes before stringB in dictionary order.
stringA > stringB	stringA comes after stringB in dictionary order.
exprA -eq exprB	Arithmetic expressions exprA and exprB are equal.
exprA -ne exprB	Arithmetic expressions exprA and exprB are not equal.
exprA -lt exprB	exprA is less than exprB .
exprA -gt exprB	exprA is greater than exprB .
exprA -le exprB	exprA is less than or equal to exprB .
exprA -ge exprB	exprA is greater than or equal to exprB .