check file already exists, other options - shell

these are the arguments that can be used while shell scripting

example:
#to check whether given path or string is a directory

-e
file exists

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

-s
file is not of size

-d
file is a directory

-b
file is a block device (floppy, cdrom, etc.)

-c
file is a character device (keyboard, modem, sound card, etc.)

-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)

-g
set-group-id (sgid) flag set on file or directory

-u
set-user-id (suid) flag set on file

-k
sticky bit set

-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 condition.

Shell Scripting - File Handling Options