'$' predefined shell variable (called as "$$"). What does it hold?
128374
what is $$ in bash?
60378
When $SHELL variable does not change when I switch shell
18316
Security implications of forgetting to quote a variable in bash/POSIX shells
7431
How does ${!#} work in bash to get the last command-line argument?
42711
What does $$ mean in the shell?
27742
What does "${-#*i}" != "$-" mean?
122288
Variable with colon dash ${VAR:-}
74331
Are there naming conventions for variables in shell scripts?
102224
Does variable=$(...) store the command or the result of the command in POSIX sh
57007
What is the meaning of $? in a shell script?
25478
What does ${1+"$@"} mean in a shell script, and how does it differ from "$@"?
32654
How to know where shell variables and functions are set?
83409
Difference between $ and # in Linux environment
45662
What is `$?` ? Is it a variable?
45816
What do $< and $@ represent in a Makefile?
2583
Quoting within $(command substitution) in Bash
9976
What is "declare" in Bash?