execute at specific time

Question

1. create a file
2. change its permissions at a specific time
3. change the permission.

At the moment this is what I have and it changes the permissions of the file but not according to the time specified.

#!/bin/bash 
$ at 13:05 
chmod 777 bin/permission.sh

Answer 1

If you want to make a file executable at 3pm, you can do:

echo chmod 777 /path/to/file | at 3pm

The at command takes a script on its standard input. So you echo the command you want to run into at and tell at when to run it.

Answer 2

You can use crontab

crontab -e

And write:

05 13 * * * chmod 0777 /full/path/to/bin/permission.sh

supposing you want it to be executed everyday at 13:05. Finally, save the file.

NOTE: The default editor seems to be "vi", if you are not comfortable with this you can change it before executing "crontab -e" with:

export EDITOR=nano

for example.