File test option in shell

These are the options to be used in conditional statement to check file attributes.

-e

file exists

example:

      if [ -b "$filename" ]
      then
        echo "$filename exist."
      fi

-a

file exists

This is same in effect to –e, but now it is discouraged to use.

-f

file is a regular file (not a directory or device file)

-s

file is not zero size

-d

file is a directory

-b

file is a “block device”

-c

file is a “character device”

-p

file is a “pipe”

-h

file is a “symbolic link”

-L

file is a symbolic link

-S

file is a “socket”

-r

file has read permission (for the user running the test)

-w

file has write permission (for the user running the test)

-x

file has execute permission (for the user running the test)

-k

sticky bit set

Commonly known as the sticky bit, the save-text-mode flag is a special type of file permission. If a file has this flag set, that file will be kept in cache memory, for quicker access.  

-O

you are owner of file

-G

group-id of file same as yours

-N

file modified since it was last read

f1 -nt f2

file f1 is newer than f2

f1 -ot f2

file f1 is older than f2

f1 -ef f2

files f1 and f2 are hard links to the same file

!

"not" -- reverses the sense of the tests above (returns true if condition absent).