linux - What does $@ mean in a shell script? - Stack Overflow The shell splits tokens based on the contents of the IFS environment variable Its default value is \t\n; i e , whitespace, tab, and newline Expanding "$@" gives you a pristine copy of the arguments passed Expanding $@ may not
What is the $? (dollar question mark) variable in shell scripting? The shell treats several parameters specially These parameters may only be referenced; assignment to them is not allowed [ ]? Expands to the exit status of the most recently executed foreground pipeline ANSI C and POSIX then recommend that: 0 means the program was successful other values: the program failed somehow
What does $# mean in shell? - Unix Linux Stack Exchange You can always check the man page of your shell man bash says: Special Parameters # Expands to the number of positional parameters in decimal Therefore a shell script can check how many parameters are given with code like this: if [ "$#" -eq 0 ]; then echo "you did not pass any parameter" fi
Difference between $ {} and $ () in a shell script - Super User The above (along with many more forms of ${parameter…something_else} constructs) are discussed at greater length in the shell’s man page, bash(1) A Note on Quotes Note that you should always quote shell variables unless you have a good reason not to, and you’re sure you know what you’re doing By contrast, while braces can be
What are the special dollar sign shell variables? - Stack Overflow $0 is the name of the shell or shell script Most of the above can be found under Special Parameters in the Bash Reference Manual Here are all the environment variables set by the shell For a comprehensive index, please see the Reference Manual Variable Index
regex - Meaning of =~ operator in shell script - Stack Overflow The return value is 0 if the string matches the pattern, and 1 otherwise If the regular expression is syntactically incorrect, the conditional expression's return value is 2 If the shell option nocasematch is enabled, the match is performed without regard to the case of alphabetic characters
Meaning of $? (dollar question mark) in shell scripts The shell treats several parameters specially These parameters may only be referenced; assignment to them is not allowed [ ]? Expands to the exit status of the most recently executed foreground pipeline ANSI C and POSIX then recommend that: 0 means the program was successful other values: the program failed somehow
shell - What does -- (double dash double hyphen) mean? - Unix . . . In man bash we can read in Shell Builtin Commands section : Unless otherwise noted, each builtin command documented in this section as accepting options preceded by -accepts --to signify the end of the options The :, true, false, and test builtins do not accept options and do not treat --specially
Bash Script : what does #! bin bash mean? - Stack Overflow Among them, there is a shell called bash which is very very common Linux and it has a long history This is a by default shell in Linux When you write a script (collection of unix commands and so on) you have a option to specify which shell it can be used Generally you can specify which shell it wold be by using Shebang(Yes that's what it's