$(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 $(date +%B).txt . 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 Reference . Shell equality operators (=, ==, -eq) Asked 12 years, 2 months ago Modified 3 years, 9 months ago Viewed 655k times
Apr 3, 2012 · What does a dollar sign followed by an at-sign (@) mean in a shell script? For example: umbrella_corp_options ?". What is the significance of this term? Aug 1, 2019 · What does echo $? mean in shell programming? true echo $? # echoes 0 false echo $? # echoes 1 From the manual: (acessible by calling man bash in your shell) ? Expands to the exit status .
Sep 17, 2012 · Meaning of "=~" operator in shell script [duplicate] Asked 13 years, 5 months ago Modified 12 years, 6 months ago Viewed 96k times 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. 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.
Jul 22, 2018 · In shell scripts, what is the difference between $@ and $*? Which one is the preferred way to get the script arguments? Are there differences between the different shell interpreters about this?
- Difference between ${} and $() in a shell script - Super User.
- What are the special dollar sign shell variables?
- Linux - What does $@ mean in a shell script?
What does a dollar sign followed by an at-sign (@) mean in a shell script? This indicates that "Shell command interception for file-modifying patterns" should be tracked with broader context and ongoing updates.
When going through one shell script, I saw the term "$?". For readers, this helps frame potential impact and what to watch next.
FAQ
What happened with Shell command interception for file-modifying patterns?
(dollar question mark) in shell scripts.
Why is Shell command interception for file-modifying patterns important right now?
Regex - Meaning of "=~" operator in shell script - Stack Overflow.
What should readers monitor next?
Meaning of "=~" operator in shell script [duplicate] Asked 13 years, 5 months ago Modified 12 years, 6 months ago Viewed 96k times.
Sources
- https://superuser.com/questions/935374/difference-between-and-in-a-shell-script
- https://stackoverflow.com/questions/5163144/what-are-the-special-dollar-sign-shell-variables
- https://stackoverflow.com/questions/20449543/shell-equality-operators-eq
- https://stackoverflow.com/questions/9994295/what-does-mean-in-a-shell-script
