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 …

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, 1 month ago Viewed 632k times

BTW, in bash a semi-colon is a statement separator, not a statement terminator, which is a new-line. So if you only have one statement on a line then the ; at end-of-line are superfluous. Not …

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.

Nov 15, 2010 · A bashism is a shell feature which is only supported in bash and certain other more advanced shells. It will not work under busybox sh or dash (which is /bin/sh on a lot of …

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 12, 2010 · What is the purpose of a command that does nothing, being little more than a comment leader, but is actually a shell builtin in and of itself? It's slower than inserting a …