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If I run
ll /usr/bin/crontab

it gives me this output:
-rwsr-sr-x 1 root root 315432 Nov 10 2007 /usr/bin/crontab

What does 's' means in the permission mask?

Why do they need to use that?

Thanks, Dan

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The s means setuid (or setgid). In this case the crontab program will run with root permissions (because root is the owner) when ran by other users.

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These are permissions as listed with the ls command.





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