`sudo which` command not finding executable that exists in regular user PATH [duplicate]

Question

I'm encountering a confusing behavior with sudo and the which command. An executable is found when running which as a regular user, but not when using sudo which, even though it's accessible when switching to an interactive root shell.

Environment:

• Linux system (CentOS/RHEL based)
• Custom application installed in non-standard directory

Code to Reproduce:

# As regular user - command is found
[user@server ~]$ which myapp
/opt/custom/apps/bin/myapp

# Using sudo with which - command NOT found
[user@server ~]$ sudo which myapp
which: no myapp in (/sbin:/bin:/usr/sbin:/usr/bin)

# But switching to interactive root shell - command IS found
[user@server ~]$ sudo -u root -i
[root@server ~]# which myapp
/opt/custom/apps/bin/myapp

Why does sudo which use a different PATH than the interactive root shell?

Answer 1

1. As root, there are more things that should be in your path. (like /sbin and /usr/sbin)
2. As root, there are things that should not be in your path. (like .)

Therefore, the path is normally reset.

The options for this are in /etc/sudoers

Better would be to tell it just which program you want to run.

Answer 2

See the section Command Environment in man sudoers.

By default, env_reset is enabled and PATH is reset to a secure value - either secure_path value or a compiled-in value if the secure_path is not set.

sudo -i keeps PATH value from the user environment.