$- (dollar hyphen) bash parameter is used to get current option flags specified during the invocation, by the set built-in command or set by the bash shell itself.
What does minus mean in bash?
1 Answer. 1. - depends on the command and how it responds to it. but it usually means the stdout/stdin in bash commands. In this case, - is the argument to the -O option, so the downloaded data is not saved in a file, but printed to stdout, so it can be piped to the tar command.Jan 21, 2013
How do I reverse search in bash?
In bash, when you use reverse-i-search, you first press Ctrl+R and then you start typing the command you was looking for. While you type, the command is appearing in console. To look for previous commands that also match your query, you press Ctrl+R as many times as you will need in order to you find your command.Aug 30, 2017
What does $? Mean?
3. 44. $? is the exit status of the most recently-executed command; by convention, 0 means success and anything else indicates failure.Aug 18, 2011
What is $@ In bash shell?
bash [filename] runs the commands saved in a file. $@ refers to all of a shell script's command-line arguments. $1 , $2 , etc., refer to the first command-line argument, the second command-line argument, etc. Place variables in quotes if the values might have spaces in them.
What does $@ mean in Linux?
$@ is nearly the same as $* , both meaning "all command line arguments". They are often used to simply pass all arguments to another program (thus forming a wrapper around that other program).Apr 3, 2012
What does $_ mean in bash?
$_ (dollar underscore) is another special bash parameter and used to reference the absolute file name of the shell or bash script which is being executed as specified in the argument list. This bash parameter is also used to hold the name of mail file while checking emails.
What does $# mean in bash?
$# is the number of arguments, but remember it will be different in a function. $# is the number of positional parameters passed to the script, shell, or shell function. This is because, while a shell function is running, the positional parameters are temporarily replaced with the arguments to the function.Jul 25, 2017
What are the variables $1 $2 $3 etc used for?
There are quite a few variables that can be used within scripts to evaluate arguments and display information about the script itself. $1, $2, $3 etc. represent the first, second, third, etc. arguments to the script.Apr 9, 2019
What does grep $1 do?
grep is a program that searches for regular expressions. The first argument for grep is the pattern to look for. In scripts and functions $1 is a reference to the first argument passed to that script or function.May 18, 2015