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Systems & Data Center · Foundational

su

The Linux substitute-user command that starts a shell as another user, root by default.

Definition

su - (or su -l) starts a login shell that loads the target user's environment; plain su keeps much of the current environment. It requires the target user's password unless run by root.

Example

su - postgres opens a login shell as the postgres account.

Exam tip

The hyphen matters: su - loads the target's full login environment, including PATH.

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