[SOLVED] script arg or parameters limitation

jao_madn · 04-22-2012, 08:47 AM

Hi,

I would like to ask some info on the script arguments/parameters. Does script arguments had limitation like inside or deep inside the loop in which it will not function as it use to be.

as an example:
$2 not working

Code:

command2 () {
for log in $LOG{1,2,3}
	do
	if [ -e $log ] && [ -s $log ]; then
	echo
	echo BEGIN $log
	grep -E "$DATE" $log | grep -E "$2"  2> $SCRIPT
	echo
	echo END $log
	echo
	fi
	done
}

$2 need to declare as another variable to work

Code:

par2=echo $2
command2 () {
for log in $LOG{1,2,3}
	do
	if [ -e $log ] && [ -s $log ]; then
	echo
	echo BEGIN $log
	grep -E "$DATE" $log | grep -E "$par2"  2> $SCRIPT
	echo
	echo END $log
	echo
	fi
	done
}

druuna · 04-22-2012, 09:25 AM

Hi,

How are you calling the command2 function?

Could it be that you're confusing arguments given to the script with those given to a function?

If you run your script like this:

Code:

./script.sh one two

one and two are represented by $1 and $2 in the script, but any function in that script isn't aware of that.

A function also uses $1, $2, etc. These hold the values the function was called with.

If you use command2 $1 $2 it will work.

Have a look at this:

Code:

#!/bin/bash

function foo() {
  echo "Inside function"
  echo $1
  echo $2
  echo $3
  echo " ------------------"
}

echo "Outside function"
echo $1
echo $2
echo $3
echo " ------------------"

foo "Hello" $2 "Bye"

Run this as: ./script.sh one two three

This is one of the reasons why it is good practise to properly name your variables, it makes things more readable and also reduces the chance of mix-ups.

Hope this helps.

jao_madn · 04-22-2012, 09:36 AM

Quote:

Originally Posted by druuna

Hi,

How are you calling the command2 function?

Could it be that you confusing arguments given to the script with those given to a function?

If you run your script like this:

Code:

./script.sh one two

one and two are represented by $1 and $2 in the script, but any function in that script isn't aware of that.

A function also uses $1, $2, etc. These hold that values the function was called with.

If you use command2 $1 $2 it will work.

Have a look at this:

Code:

#!/bin/bash

function foo() {
  echo "Inside function"
  echo $1
  echo $2
  echo $3
  echo " ------------------"
}

echo "Outside function"
echo $1
echo $2
echo $3
echo " ------------------"

foo "Hello" $2 "Bye"

Run this as: ./script.sh one two three

This is one of the reasons why it is good practise to properly name your variables, it makes things more readable and also reduces the chance of mix-ups.

Hope this helps.

@druuna: thanks, very much appreciated, you just save me some time digging/reading in the advance shell script guide about functions..

druuna · 04-22-2012, 09:39 AM

You're welcome

Just in case:

Bash resources:

BTW: Can you put up the [SOLVED] tag.
first post -> Thread Tools -> Mark this thread as solved