Learning the bash Shell, Second Edition

Test Operators

Table 2.5 lists the operators that are used with test and the [...] construct. They can be logically combined with -a (“and”) and -o (“or”) and grouped with escaped parenthesis (\( ... \)). The string comparisons < and > are not available in versions of bash prior to 2.0.

Table B-5. Test Operators

Operator	True If...
-b file	file exists and is a block device file
-c file	file exists and is a character device file
-d file	file exists and is a directory
-e file	file exists
-f file	file exists and is a regular file
-g file	file exists and has its setgid bit set
-G file	file exists and is owned by the effective group ID
-k file	file exists and has its sticky bit set
-L file	file exists and is a symbolic link
-n string	string is non-null
-O file	file exists and is owned by the effective user ID
-p file	file exists and is a pipe or named pipe (FIFO file)
-r file	file exists and is readable
-s file	file exists and is not empty
-S file	file exists and is a socket
-t N	File descriptor N points to a terminal
-u file	file exists and has its setuid bit set
-w file	file exists and is writeable
-x file	file exists and is executable, or file is a directory that can be searched
-z string	string has a length of zero
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
stringA = stringB	stringA equals stringB
stringA != stringB	stringA does not match stringB ...