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Test Operators
Table B-6 lists the operators that are used with test and the [...] and [[...]] constructs. They can be logically combined with -a ("and") and -o ("or") and grouped with escaped parenthesis (\( ... \)). The string comparisons < and > and the [[...]] construct are not available in versions of bash prior to 2.0.
Table B-6. Test operators
Operator
True if...
-a file
file exists
-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; same as -a
-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
-h file
file exists and is a symbolic link
-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
-N file
file was modified since it was last read
-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 modification time is newer than fileB
fileA -ot fileB
fileA modification time is older than fileB
fileA -ef fileB
fileA and fileB point to the same file
stringA = stringB
stringA equals stringB (POSIX version)
stringA == stringB
stringA equals stringB
stringA != stringB
stringA does not match stringB
stringA =~ regexp
stringA matches the extended regular expression regexp[3]
stringA < stringB
stringA sorts before stringB lexicographically
stringA > stringB
stringA sorts after stringB lexicographically
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
exprA -a exprB
exprA is true and exprB is true
exprA -o exprB
exprA is true or exprB is true
[3] Only available in bash version 3.0 and later. May only be used inside [[...]].
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