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Conditional Expressions Test
Conditional expressions are used by the [] compound
command and the test command to test file attributes
and perform string and arithmetic comparisons.
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Example:
test -a file_name
Options:
-a file
True if file exists.
-b file
True if file exists and is a block special file.
-c file
True if file exists and is a character special file.
-d file
True if file exists and is a directory.
-e file
True if file exists.
-f file
True if file exists and is a regular file.
-g file
True if file exists and is set-group-id.
-h file
True if file exists and is a symbolic link.
-k file
True if file exists and its ``sticky'' bit is set.
-p file
True if file exists and is a named pipe (FIFO).
-r file
True if file exists and is readable.
-s file
True if file exists and has a size greater than zero.
-t fd True if file descriptor fd is open and refers to a terminal.
-u file
True if file exists and its set-user-id bit is set.
-w file
True if file exists and is writable.
-x file
True if file exists and is executable.
-O file
True if file exists and is owned by the effective user id.
-G file
True if file exists and is owned by the effective group id.
-L file
True if file exists and is a symbolic link.
-S file
True if file exists and is a socket.
-N file
True if file exists and has been modified since it was last read.
file1 -nt file2
True if file1 is newer (according to modification date) than file2,
or if file1 exists and file2 does not.
file1 -ot file2
True if file1 is older than file2,
or if file2 exists and file1 does not.
file1 -ef file2
True if file1 and file2 refer to the same device and inode numbers.
-o optname
True if shell option optname is enabled.
-z string
True if the length of string is zero.
-n string
string True if the length of string is non-zero.
string1 == string2
True if the strings are equal.
string1 != string2
True if the strings are not equal.
string1 < string2
True if string1 sorts before string2 lexicographically
string1 > string2
True if string1 sorts after string2 lexicographically
arg1 OP arg2
OP is one of -eq, -ne, -lt, -le, -gt, or -ge.
These arithmetic binary operators return true if
arg1 is equal to, not equal to, less than, less than
or equal to, greater than, or greater than
or equal to arg2, respectively.
Arg1 and arg2 may be positive or negative integers.
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