What does $# mean in shell? I have code such as if [ $# -eq 0 ] then I want to understand what $# means, but Google search is very bad for searching these kinds of things.

Feb 20, 2011 · When going through one shell script, I saw the term "$?". What is the significance of this term?

May 8, 2012 · I understand the basic difference between an interactive shell and a non-interactive shell. But what exactly differentiates a login shell from a non-login shell? Can you give …

Oct 26, 2023 · I have a script that parses a rudimentary .env file and exports its contents as environment variables, before taking further action: set -eu test -f .env && load_dotenv …

Aug 2, 2025 · When it comes to shell scripts it's difficult to support both short options and long options. I usually pick one or the other and use getopt or getopts as appropriate.

I have a file, f1.txt: ID Name 1 a 2 b 3 g 6 f The number of spaces is not fixed. What is the best way to replace all the white spaces with one space using only tr? ...

What can you do with the eval command? Why is it useful? Is it some kind of a built-in function in bash? There is no man page for it..

Jul 30, 2025 · This [escaping a colon in PATH on UNIX] is impossible according to the POSIX standard. This is not a function of a specific shell, PATH handling is done within the execvp …

See here if you're confused about the differences b/w Bash's trap command and 0 vs. a signal 0 from kill: What is signal 0 in a trap command?

Sep 1, 2017 · I find myself constantly looking up the syntax of find . -name "FILENAME" -exec rm {} \\; mainly because I don't see how exactly the -exec part works. What is the meaning of the …