How do I find out number of arguments passed to my bash function called foo() under Unix like operating systems?
Each bash shell function has the following set of shell variables:
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[a] All function parameters or arguments can be accessed via $1, $2, $3,..., $N.
[b] $* or $@ holds all parameters or arguments passed to the function.
[c] $# holds the number of positional parameters passed to the function.
[d] An array variable called FUNCNAME ontains the names of all shell functions currently in the execution call stack.
Example
Create a shell script as follows:
#!/bin/bash# Purpose: Demo bash function# Author: nixCraft# -----------------------------## Define a function called foo()
foo(){echo"Function name: ${FUNCNAME}"echo"The number of positional parameter : $#"echo"All parameters or arguments passed to the function: '$@'"echo}## Call or invoke the function #### Pass the parameters or arguments ##
foo nixCraft
foo 12345
foo "this""is""a""test"
#!/bin/bash
# Purpose: Demo bash function
# Author: nixCraft
# ----------------------------- ## Define a function called foo()
foo(){
echo "Function name: ${FUNCNAME}"
echo "The number of positional parameter : $#"
echo "All parameters or arguments passed to the function: '$@'"
echo
} ## Call or invoke the function ##
## Pass the parameters or arguments ##
foo nixCraft
foo 1 2 3 4 5
foo "this" "is" "a" "test"
Run it as follows: $ chmod +x script.name.here $ ./script.name.here Sample outputs: Fig.01: Bash function displaying number of arguments passed to foo()
The author is the creator of nixCraft and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.
1 comment
Try using the special variable ${#}.
function foo {
echo “N. of Args: ${#}”
}
$ foo a b c
3