Condition hints:
- -b file = True if the file exists and is block special file.
- -c file = True if the file exists and is character special file.
- -d file = True if the file exists and is a directory.
- -e file = True if the file exists.
- -f file = True if the file exists and is a regular file
- -g file = True if the file exists and the set-group-id bit is set.
- -k file = True if the files’ “sticky” bit is set.
- -L file = True if the file exists and is a symbolic link.
- -p file = True if the file exists and is a named pipe.
- -r file = True if the file exists and is readable.
- -s file = True if the file exists and its size is greater than zero.
- -s file = True if the file exists and is a socket.
- -t fd = True if the file descriptor is opened on a terminal.
- -u file = True if the file exists and its set-user-id bit is set.
- -w file = True if the file exists and is writable.
- -x file = True if the file exists and is executable.
- -O file = True if the file exists and is owned by the effective user id.
- -G file = True if the file exists and is owned by the effective group id. file1
- –nt file2 = True if file1 is newer, by modification date, than file2. file1 ot file2 = True if file1 is older than file2. file1 ef file2 = True if file1 and file2 have the same device and inode numbers.
- -z string = True if the length of the string is 0.
- -n string = True if the length of the string is non-zero.
- string1 = string2 = True if the strings are equal.
- string1 != string2 = True if the strings are not equal.
- !expr = True if the expr evaluates to false.
- expr1 –a expr2 = True if both expr1 and expr2 are true.
- expr1 –o expr2 = True is either expr1 or expr2 is true.