CODEWITHSUNDEEP
unixshellenvironment-variablessudo
Jörg Haubrichs
Jörg Haubrichs

Reputation: 2243

Getting $USER inside shell script when running with sudo?

How do I get the correct $USER if I run a shell script with sudo ?

I run them as postinstall scripts in a Mac install package, where they are being sudo-ed automatically, but I need to do stuff with the username.

$HOME is correct, though. The inelegant method would be to extract the name from the home path, but I wonder if there is a natural way to do this.

I can't influence the way the scripts are being called, as it's an automatic call inside the installer.

Upvotes: 47

Views: 25108

Answers (4)

Gauthier
Gauthier

Reputation: 41955

You can use $(logname), which returns your login name even if you are currently sudoing.

Upvotes: 29

dz.
dz.

Reputation: 1326

On my system the variable $SUDO_USER is set to the caller's user name.

You shouldn't extract the username from the ${HOME} variable directly. It's being configured and not calculated. To Extract the username you could take a look into /etc/passwd file, but this is very system dependent, e.g. sometimes you have to look into a LDAP directory or the entries are propagated through NIS ...

Upvotes: 46

Jim S.
Jim S.

Reputation: 91

SUDO_USER isn't portable. It's unset on Fedora 17.

The $USER and $UID variables aren't predictable when invoking sudo either. Some distros report the sudoer, others report the root user.

It's by no means perfect, but you could use test -w ~root && echo I have write access to ~root.

Upvotes: 9

brianegge
brianegge

Reputation: 29872

Inspect the variable SUDO_USER.

http://www.gratisoft.us/sudo/man/sudo.html#environment

Another way to get the user is via the who command. This is useful sometimes when you don't care if the user has sudo'd or not.

who -m | awk '{print $1;}'

Upvotes: 19

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