Question

should be in Linux, please

Write a shell program named A1L21

Your program should set permissions for a file whose name is given as

an argument to your program. The permissions must be changed using a

SINGLE chmod command, and must be set to EXACTLY rw for owner and group

and x for others.

Your program should NOT show any error messages on the screen, even if

the given file does not exist, etc.

Answer 1

Code inside the shell program-

#!/bin/bash
chmod 661 $1 2> /dev/null

Explanation -
chmod - used to change file permissions
661 - represents the three sets of permission (owner, group and other). 6 is for read and write permission. 1 is for execute permission.
$1 - this has the argument given to the shell program.
2> /dev/null this part is used to suppress the error messages when a file does not exist etc.
> this is the redirect operator .
2 this is a reference to standard error output stream.
2> redirect the output stream.
/dev/null this is a null device it eats up any input provided to it.
by combining these we can throw away the output error messages.

** Tested in Ubuntu **