bash call function with arguments

Here’s how to call a function in Bash, with or without arguments. The function badUsage may or may not make an argument. You can use $1, $2, $3 and so on to access the arguments inside the function. Bash Functions – In this Bash Tutorial, we shall learn about functions in Bash Shell Scripting with the help of syntax and examples.. About Bash Functions. When I do to call the function I just need to pass the values that I want for $1 $2 and so forth. If you don't modify the argument in any way, there is no need to copy it to a local variable - simply echo "Hello, $1". You should use getopt or getopts for processing options. badUsage "Option/command not recognized." If an argument is passed to the function, it is printed as a message. Passing Arguments in Bash Functions. We also have an option to pass input arguments to the bash function. Each bash function has its own set of positioned arguments just like that of the main script file. Put any parameters for a bash function right after the function’s name, separated by whitespace, just like you were invoking any shell script or command. – kashyap Apr 24 '17 at 21:57 @kashyap case doesn't loop. Function has to be defined in the shell script first, before you can use it. You don’t put parentheses around the arguments like you might expect from some programming languages. Arguments could be passed to functions and accessed inside the function as $1, $2 etc. badUsage Then there is the function for … case statement is used … Here, 4 options are used which are β€˜i’, β€˜n’, β€˜m’ and β€˜e’ . So now about arguments with bash functions. β€˜getopts’ function is used with while loop to read command line argument options and argument values. Call bash function with arguments. In the subscripts or functions, the $1 and $2 will represent the parameters, passed to the functions, as internal (local) variables for this subscripts. Create a bash file and add the following script to understand the use of getopts function. The scope of a local variable limited to function while you can access global variables out of function. Imagine you are trying to write a function to compare two integers but these integers will be provided by end user as command line argument; So how will function access these integer values for comparison? Here is an example. The $@ variable expands to all command-line parameters separated by spaces. Bash Functions. Passing inputs to a function is no different from passing arguments to a Bash script: function simple_inputs() { echo "This is the first argument [$1]" echo "This is the second argument [$2]" echo "Calling function with $# arguments" } simple_inputs one 'two three' Let’s take a … Why would you need that you ask? Don’t … This is a while loop that uses the getopts function and a so-called optstringβ€”in this case u:d:p:f:β€”to iterate through the arguments. To do the same without quotes, they'd do program -p hello_world -tSu, where the function program itself gets three arguments. (Or if you want to lock yourself to exactly three arguments, $1 to $3.) You can pass arguments to the bash function easily by writing them with double quotes after function name separated by space. abc "$@" When using $@, you should (almost) always put it in double-quotes to avoid misparsing of arguments containing spaces or wildcards (see below).This works for multiple arguments. It is also portable to all POSIX-compliant shells. $1 only contains one of them, in both Bash and Zsh. 2 - Arguments in bash functions. To pass all the arguments on, you have to use $@. after having the functions above the case it worked, but if I give the two options at a time only the first option is working!!! Note: for arguments more than 9 $10 won't work (bash will read it as $10), you need to do ${10}, ${11} and so on. 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