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- bash - What are the special dollar sign shell variables . . . - Stack . . .
In Bash, there appear to be several variables which hold special, consistently-meaning values For instance, myprogram amp;; echo $! will return the PID of the process which backgrounded myprog
- bash - What is the purpose of in a shell command? - Stack Overflow
As far as I know, using amp; after the command is for running it in the background Example of amp; usage: tar -czf file tar gz dirname amp; But how about amp; amp;? (example)
- 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" are pattern matching, other three are string equality:
- Whats the difference between lt; lt;, lt; lt; lt; and lt; lt; in bash?
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 observed via tracing system calls with strace command Replace bash with sh to see how bin sh performs this redirection $ strace -e open,dup2,pipe,write -f bash -c 'cat <<EOF > test
- 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 thus only the left-hand side of the or runs, since that succeeds the right-hand side doesn't need to run
- 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 compliant, stay away from it; otherwise, it's basically down to personal preference Note that the arithmetic substitution expression $((
- What do the -n and -a options do in a bash if statement?
In bash the test command will be a built-in command; try type [to learn its type For built-in commands help will show usage, so also run help [ to see documentation Your system probably also has a bin [ and a bin test and if you man test you can see the manuals for those
- How to compare strings in Bash - Stack Overflow
Bash always seemed backward with numeric evaluations using an operator consisting of a string (-eq) and string comparisons using a numeric operator "==" or "=" just you mess you up If you ask me I'd say the problem is the distro swapping out bash That is just my opinion, but this is my fix ln bin bash bin sh -sf
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