Linux - ncdu with sudo

[Justinzobel]

Additional Info

• I am using Windows Subsystem for Linux

Output of brew config

N/A

Output of brew doctor

N/A

Description of issue

How does one use sudo with ncdu to look at filesystem directories, e.g. sudo ncdu /?

[ZhongRuoyu]

If your problem is sudo complaining it cannot find ncdu, this is because sudo resets the PATH. Instead of sudo ncdu / you can do sudo `which ncdu` /.

[Justinzobel]

Thanks! For me on fish it was sudo $(which ncdu) /

[gromgit]

sudo only resets PATH after it searches for the specified command, so substituting which ncdu should have no net effect.

@Justinzobel, what's the exact error you see with sudo ncdu /?

[Justinzobel]

Yeah it was a case of not in path.

[ZhongRuoyu]

sudo only resets PATH after it searches for the specified command

If secure_path is set in sudoers, then sudo only searches for commands from the paths set there. From manpage:

secure_path
If set, sudo will use this value in place of the user's PATH environment variable. There are two basic use cases for secure_path:

1. To make it possible for sudo to find system administrator commands located in directories that may not be in the default user path, such as /usr/sbin.
2. To help protect scripts and programs that execute other commands without first setting PATH to a safe value. Otherwise, a user with limited privileges may be able to run arbitrary commands by manipulating the PATH if the command being run executes other commands without using a fully-qualified path name.

Users in the group specified by the exempt_group option are not affected by secure_path. This option is disabled by default.

It's not set by default on macOS, but some distros, like Debian, do this:

Defaults	secure_path="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"

I believe OP's sudo ncdu invocation failed because of this.