24

I have added a custom path to PATH variable in my /root/.bashrc file

When i do sudo su; echo $PATH, it shows the entry, '/path/to/custom/bins'.

But i do sudo sh -c 'echo $PATH', it shows, /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

The folder paths added in .bashrc file are not visible.

Doesn't sudo command have the same environment as a root user?

30

.bashrc is a configuration file of bash, only when it's executed interactively. It's only loaded when you start bash, not when you run some other program such as sh (not even if bash is invoked via the name sh). And it's only loaded when bash is interactive, not when it's executing a script or a command with -c.

sudo sh -c 'echo $PATH' or sudo bash -c 'echo $PATH' doesn't invoke an interactive shell, so .bashrc is not involved.

sudo su; echo $PATH runs an interactive instance of root's shell. If that's bash, then ~root/.bashrc is loaded. This snippet executes echo $PATH once this interactive shell terminates, so whatever happens in the interactive shell has no influence on what the snippet prints at the end. But if you type echo $PATH at the prompt of the interactive shell started by sudo su, you will see the value set by ~root/.bashrc.

Since .bashrc is invoked in each interactive shell, not by login shells (not even by interactive login shells, which is a design defect in bash), it's the wrong place to define environment variables. Use .bashrc for interactive bash settings such as key bindings, aliases and completion settings. Set environment variables in files that are loaded when you log in: ~/.pam_environment or ~/.profile.

So set PATH in .profile instead of .bashrc, and either run a login shell with sudo -i 'echo $PATH', or explicitly source .profile with sudo sh -c '. ~/.profile; echo $PATH'.

  • 1
    has addressed many relevant points about shells.... thanks.... – Madhavan Sep 9 '15 at 2:40
  • 1
    How do I add it to .profile? Do you mean /root/.profile or /home/user/.profile? I tried adding export PATH=$PATH:/mydir to both. Didn't work. I tried without export, that didn't work either. – falsePockets Jan 22 at 6:06
  • @falsePockets Didn't work for what? You should ask a new question and explain exactly what you're doing. – Gilles Jan 22 at 7:45
  • The thing which didn't work is exactly the same thing OP is trying to do. I am trying to add a directory to the PATH of my superuser. I should not ask a new question, since that question would be a duplicate of this question. – falsePockets Jan 23 at 1:09
  • @falsePockets But evidently you aren't doing the same thing to reach the superuser account. And since you didn't say what you're doing, I can't help you other than repeating what's already in my answer. – Gilles Jan 23 at 9:11
13

Look at the -E and -i options.

-E : Indicates to the security policy that the user wishes to preserve their existing environment variables. The security policy may return an error if the user does not have permission to preserve the environment.

-i : Run the shell specified by the target user's password database entry as a login shell. This means that login-specific resource files such as .profile or .login will be read by the shell. If a command is specified, it is passed to the shell for execution via the shell's -c option. If no command is specified, an interactive shell is executed. sudo attempts to change to that user's home directory before running the shell. The command is run with an environment similar to the one a user would receive at log in. The Command environment section in the sudoers(5) manual documents how the -i option affects the environment in which a command is run when the sudoers policy is in use.

2

You could to sudo bash, which does read the bash startup files as documented in the bash manual page/documentation. Please note, however, that it may not set the HOME environment variable correctly. This can be fixed in the system-wide bash startup file (in /etc, exact location depends on distro) - test whether the $uid is 0.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.