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Full Discussion: Getting number of argument passed to a shell script
Top Forums Shell Programming and Scripting Getting number of argument passed to a shell script Post 303003336 by bakunin on Tuesday 12th of September 2017 01:21:10 PM
Old 09-12-2017
Quote:
Originally Posted by mukulverma2408
Any idea what am I doing wrong?
Yes, and as you have already received the solution i wil concentrate on explaining the reason:

When you invoke a process with some arguments these arguments become part of the "process environment". Inside a script you can then use special variables ("$@", "$*", "$1", "$2", ...) to pull these arguments out of the environment or get ("$#") the number of parameters passed.

But every time you invoke a shell function inside a script this function gets its own environment of sorts and all the special variables "$1", "$2", etc. and "$#" describe what is passed as argument to the function instead of what is passed to the main script. Look at the following sample script:

Code:
#! /bin/bash

subfunc()
{
    echo "inside subfunc"
    echo "Number of arguments passed: $#"
    echo "argument 1: $1"
    echo "argument 2: $2"
    echo "argument 3: $3"
}

# main part
echo "inside main"
echo "Number of arguments passed: $#"
echo "argument 1: $1"
echo "argument 2: $2"
echo "argument 3: $3"

subfunc a b c
subfunc X Y

And its output will be:

Code:
# ./sample.sh foo bar baz blah
inside main
Number of arguments passed: 4
argument 1: foo
argument 2: bar
argument 3: baz
inside subfunc
Number of arguments passed: 3
argument 1: a
argument 2: b
argument 3: c
inside subfunc
Number of arguments passed: 2
argument 1: X
argument 2: Y
argument 3:

I hope this helps.

bakunin
This User Gave Thanks to bakunin For This Post:
mukulverma2408
 

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LEARN ABOUT LINUX

npm-run-script

NPM-RUN-SCRIPT(1)                                                                                                                NPM-RUN-SCRIPT(1)

NAME

       npm-run-script - Run arbitrary package scripts

SYNOPSIS

         npm run-script <command> [--silent] [-- <args>...]

         alias: npm run

DESCRIPTION

       This  runs  an  arbitrary  command  from  a  package's  "scripts" object.  If no "command" is provided, it will list the available scripts.
       run[-script] is used by the test, start, restart, and stop commands, but can be called directly, as well. When the scripts in  the  package
       are printed out, they're separated into lifecycle (test, start, restart) and directly-run scripts.

       As  of  `  https://blog.npmjs.org/post/98131109725/npm-2-0-0, you can use custom arguments when executing scripts. The special option -- is
       used by getopt https://goo.gl/KxMmtG to delimit the end of the options. npm will pass all the arguments  after  the  --  directly  to  your
       script:

         npm run test -- --grep="pattern"

       The arguments will only be passed to the script specified after npm run and not to any pre or post script.

       The  env  script  is a special built-in command that can be used to list environment variables that will be available to the script at run-
       time. If an "env" command is defined in your package, it will take precedence over the built-in.

       In addition to the shell's pre-existing PATH, npm run adds node_modules/.bin to the PATH provided to  scripts.  Any  binaries  provided  by
       locally-installed  dependencies  can  be used without the node_modules/.bin prefix. For example, if there is a devDependency on tap in your
       package, you should write:

         "scripts": {"test": "tap test/*.js"}

       instead of

         "scripts": {"test": "node_modules/.bin/tap test/*.js"}

       to run your tests.

       The actual shell your script is run within is platform dependent. By default, on Unix-like systems it is the /bin/sh command, on Windows it
       is    the    cmd.exe.     The    actual    shell    referred    to    by    /bin/sh    also    depends    on   the   system.    As   of   `
       https://github.com/npm/npm/releases/tag/v5.1.0 you can customize the shell with the script-shell configuration.

       Scripts are run from the root of the module, regardless of what your current working directory is when you call npm run. If you  want  your
       script  to use different behavior based on what subdirectory you're in, you can use the INIT_CWD environment variable, which holds the full
       path you were in when you ran npm run.

       npm run sets the NODE environment variable to the node executable with which npm is executed. Also, if the  --scripts-prepend-node-path  is
       passed,  the  directory  within  which node resides is added to the PATH. If --scripts-prepend-node-path=auto is passed (which has been the
       default in npm v3), this is only performed when that node executable is not found in the PATH.

       If you try to run a script without having a node_modules directory and it fails, you will be given a warning to run npm  install,  just  in
       case you've forgotten.

       You can use the --silent flag to prevent showing npm ERR! output on error.

       You  can  use  the --if-present flag to avoid exiting with a non-zero exit code when the script is undefined. This lets you run potentially
       undefined scripts without breaking the execution chain.

SEE ALSO

       o npm help 7 scripts

       o npm help test

       o npm help start

       o npm help restart

       o npm help stop

       o npm help 7 config

                                                                   January 2019                                                  NPM-RUN-SCRIPT(1)
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