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EUID is not the same as UID. At what context are these both are used in the script?
I tried to get the values by echo "UID is $UID and EUID is $EUID", but only space came as output. My machine runs Ubuntu 12.04 LTS. Seen at some sites that this is usually used to check whether it is root user and all but not able to get proper difference.
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Effective user ID The effective UID ( euid ) of a process is used for most access checks. It is also used as the owner for files created by that process.
EUID is the Effective User ID. The effective user ID describes the user whose file access permissions are used by the process. RUID is the Real User ID. The real user ID identifies the user who created the process.
EUID(Effective User ID) Generally, UID and EUID is the same. EUID is changed by executable file that is configured SetUID authority. EUID temporarily stores another account's UID. The authority of a process is determined according to the UID stored in the EUID.
Users created by root have euid=0(root) egid=2(bin)!!! - Operating Systems.
They're different when a program is running set-uid. Effective UID is the user you changed to, UID is the original user.
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It only works on bash, not in dash (in Debian based distros as Ubuntu sh is usually a symlink to dash).
If you are running the script interactively you might not have bash configured as your default shell, run bash before trying.
If you are running it from console:
bash script.sh If you are running it using its path (for example ./script.sh) ensure the first line of the script is:
#!/bin/bash And not:
#!/bin/sh For a more generic way to do it check: https://askubuntu.com/questions/15853/how-can-a-script-check-if-its-being-run-as-root
In that post the command id is mentioned, where:
id -u # is the EUID id -u -r # is the UID If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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