bash - What are the special dollar sign shell variables ... - Stack ...
Sep 14, 2012 · In Bash, there appear to be several variables which hold special, consistently-meaning values. For instance, ./myprogram &; echo $! will return the PID of the process …
bash - What is the purpose of "&&" in a shell command? - Stack …
Oct 27, 2021 · As far as I know, using & after the command is for running it in the background. Example of & usage: tar -czf file.tar.gz dirname & But how about …
shell - Bash regex =~ operator - Stack Overflow
The [[ ]] is treated specially by bash; consider that an augmented version of [ ] construct: [ ] is actually a shell built-in command, which, can actually be implemented as an external …
bash - Shell equality operators (=, ==, -eq) - Stack Overflow
If not quoted, it is a pattern match! (From the Bash man page: "Any part of the pattern may be quoted to force it to be matched as a string."). Here in Bash, the two statements yielding "yes" …
Meaning of $? (dollar question mark) in shell scripts
Aug 1, 2019 · In Bash, when you hit enter, a fork + exec + wait happens like above, and bash then sets $? to the exit status of the forked process. Note: for built-in commands like echo, a …
How do AND and OR operators work in Bash? - Stack Overflow
In bash, && and || have equal precendence and associate to the left. See Section 3.2.3 in the manual for details. So, your example is parsed as $ (echo this || echo that) && echo other And …
What's the difference between <<, <<< and < < in bash?
Sep 27, 2015 · In bash these are implemented via temp files, usually in the form /tmp/sh-thd.<random string>, while in dash they are implemented as anonymous pipes. This can be …
linux - What does $@ mean in a shell script? - Stack Overflow
Apr 3, 2012 · (View Special parameters - Bash Manual) For instance, if you call ./someScript.sh foo bar then $@ will be equal to foo bar. If you do:./someScript.sh foo bar and then inside …
An "and" operator for an "if" statement in Bash - Stack Overflow
Modern shells such as Bash and Zsh have inherited this construct from Ksh, but it is not part of the POSIX specification. If you're in an environment where you have to be strictly POSIX …
linux - Difference between ${} and $() in Bash - Stack Overflow
your understanding is right. For detailed info on {} see bash ref - parameter expansion 'for' and 'while' have different syntax and offer different styles of programmer control for an iteration. …