Apr 3, 2012 · What does a dollar sign followed by an at-sign (@) mean in a shell script? For example: umbrella_corp_options $@

I'm trying to learn shell scripting, and I need to understand someone else's code. What is the $? variable hold? I can't Google search the answer because they block punctuation characters.

$(command) is “command substitution”. As you seem to understand, it runs the command, captures its output, and inserts that into the command line that contains the $(…); e.g., $ ls -ld …

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?

Shell equality operators (=, ==, -eq) Asked 11 years, 6 months ago Modified 3 years ago Viewed 630k times

Shell - "Shell" is a program, which facilitates the interaction between the user and the operating system (kernel). There are many shell implementations available, like sh, Bash, C shell, Z …

Oct 27, 2021 · 180 command-line - what is the purpose of &&? In shell, when you see $ command one && command two the intent is to execute the command that follows the && only if the first …

Sep 14, 2012 · $! is the PID of the most recent background command. $0 is the name of the shell or shell script. Most of the above can be found under Special Parameters in the Bash …

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..