Getting number of argument passed to a shell script Post: 303003336

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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

09-12-2017

Registered User

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

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LEARN ABOUT OPENSOLARIS

echo

echo(1B)					     SunOS/BSD Compatibility Package Commands						  echo(1B)

NAME

       echo - echo arguments to standard output

SYNOPSIS

       /usr/ucb/echo [-n] [argument]

DESCRIPTION

       echo writes its arguments, separated by BLANKs and terminated by a NEWLINE, to the standard output.

       echo  is useful for producing diagnostics in command files and for sending known data into a pipe, and for displaying the contents of envi-
       ronment variables.

       For example, you can use echo to determine how many subdirectories below the root directory (/) is your current directory, as follows:

	   o	  echo your current-working-directory's full pathname

	   o	  pipe the output through tr to translate the path's embedded slash-characters into space-characters

	   o	  pipe that output through wc -w for a count of the names in your path.

		    example% /usr/bin/echo "echo $PWD | tr '/' ' ' | wc -w"

       See tr(1) and wc(1) for their functionality.

       The shells csh(1), ksh(1), and sh(1), each have an echo built-in command, which, by default, will have precedence, and will be  invoked	if
       the  user  calls  echo without a full pathname. /usr/ucb/echo and csh's echo() have an -n option, but do not understand back-slashed escape
       characters. sh's echo(), ksh's echo(), and /usr/bin/echo, on the other hand, understand the  black-slashed  escape  characters,	and  ksh's
       echo() also understands a as the audible bell character; however, these commands do not have an -n option.

OPTIONS

       -n    Do not add the NEWLINE to the output.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWscpu			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       csh(1), echo(1), ksh(1), sh(1), tr(1), wc(1), attributes(5)

NOTES

       The -n option is a transition aid for BSD applications, and may not be supported in future  releases.

SunOS 5.11							    3 Aug 1994								  echo(1B)