Is there any potential negative effect of adding something to the PATH variable that is not yet installed on the system?

I’ve added LaTeX to the PATH variable, but as I’m transferring my shell configuration to multiple computers, LaTeX is not installed on all of them. Besides the obvious consequence of being unable to access the software, could there be any additional negative effects of having the PATH variable configured when the software it refers to is not present on the system?

My .zshenv file:

# TeX Live
export PATH=$PATH:/usr/local/texlive/2023/bin/x86_64-linux
Asked By: Zoltan King

||

None. Your shell will spend ~0.00005 seconds trying to open this location, fail and move on.

The only real possible issue could arise if this location is on an inaccessible remote filesystem. This may result in a minute long delay each time you try to autocomplete a command.

Answered By: Artem S. Tashkinov

Adding a directory to $PATH adds overhead to the process of running programs. The shell tries to optimize this away, but even outside the shell, this overhead is typically insignificant, and even more so for a directory that doesn’t exist.

Adding the same directory multiple times (as your example has the potential to do) is ugly, but still typically insignificant for performance.

There are security implications to adding an untrusted directory to your path, but I think those don’t apply in this case as it is a non-existent directory rather than untrusted, and the potential parents should be root owned.

Probably the very worst possible outcome would be if the disk the directory was on happened to be on a failing disk (for instance, a NFS mount point to an unresponsive server), but this is not a general case. (The result would be very slow or possibly failed logins.)

Answered By: user10489

This can have a few potential negative effects, but actually not significant.

  1. Whenever you try to run a command that relies on the software in the added directory but is not installed, you will likely receive error messages indicating that the command or executable cannot be found.

  2. If you have a command or executable name in the added directory that conflicts with an existing command on the system, it may lead to unexpected behavior.

  3. When the shell encounters a command, it searches for it in the directories listed in the PATH variable. If the software you’re referencing is not installed, the shell will have to search through all the directories in the PATH before determining that the command is not available. This additional search time can lead to a slight delay in command execution.

You can add an if statement to check if the software is present before performing the export.

If you are transferring your shell configuration to multiple computers, you may consider creating separate configuration files for each computer and customizing the PATH variable accordingly based on the software available on each system.

Or include additional checks in your shell configuration to verify the presence of required software or directories.

Answered By: Blockchain Office

Depending on where you place this in your path, and if the directory / files matching that path can be created by a regular user, there might be a security issue.

If it is close to the beginning of the path, then there is the possibility that a person with sufficient permissions to create a directory to match the path, and executables within that directory could place script named after a commonly trusted executable like ls to be called prior to the actual ls.

Normally, this kind of attack is for information gathering among other users who eventually will type the command. The fake ls could fetch user information, run commands as that user, and even send such information off system. Normally such scripts will also run the real ls and pipe the reply back to the console, to delay the discovery of interception.

Answered By: Edwin Buck
Categories: Answers Tags: ,
Answers are sorted by their score. The answer accepted by the question owner as the best is marked with
at the top-right corner.