How to pass an argument to a variable that has been assigned a script?

abhiJ · 10-25-2013, 12:33 AM

Hello everyone,

i am a newbie to shell scripting..i am trying to pass an argument to a variable which i've assigned a script. My script looks like this :

$ a=`func_unload()
> {
> if [[ $# -eq 0 ]]
> then
> echo "No argument passed"
> exit
> fi
>
> echo $1
> sqlplus -S scott/tiger@abiorcl <<EOF
> set echo off head off feedback off pagesize 0 linesize 1000 space 0
> trimspool on
> spool job_upload_$1.dat
> select
> E.elapsed_time||'|'||SCOTT.DIM_JOB_DEF.job_def <
> from SCOTT.FCT_JOB_INSTANCE,SCOTT.DIM_JOB_DEF where
> to_char(start_datetime,'mon')='$1' and SCOTT.FCT_JOB_INSTANCE.job_def_id =
> SCOTT.DIM_JOB_DEF.job_def_id;
> spool off
> exit;
> EOF
>
> }
> func_unload $1`

$

i tried a few options like :

$ echo $(a jan)

and

$ echo $a $jan

but nothing seems to work. Pls help me out!!!

pan64 · 10-25-2013, 12:37 AM

I do not really understand, but probably:

Code:

func_unload {
...
}
a=`func_unload $1`

please tell us what is your goal, what do you want to achieve (how should it work?)

abhiJ · 10-25-2013, 12:53 AM

Quote:

Originally Posted by pan64

I do not really understand, but probably:

Code:

func_unload {
...
}
a=`func_unload $1`

please tell us what is your goal, what do you want to achieve (how should it work?)

i recently found out that we can run certain commands by assigning them to a variable, for example :

$ abc=`ls |wc -l` will return total no. of files when we do :

$ echo $abc

so tried to assign a whole script to the variable 'a' as posted. this script will accept command line arguments like 'jan' or 'feb' or any name of a month when running via a editor like 'vi'. So i tried to pass arguments to the variable as i would have done when running the script normally. Is there a way to do so?? I hope you understand my point now...!!!

pan64 · 10-25-2013, 01:06 AM

there is a way to do that, but this is not the usual way (I mean assign a script to a variable is quite unusual).
you may try eval $variable to achieve something like that, but it is not really recommended and possibly unsafe.

abhiJ · 10-25-2013, 01:10 AM

Quote:

Originally Posted by pan64

there is a way to do that, but this is not the usual way (I mean assign a script to a variable is quite unusual).
you may try eval $variable to achieve something like that, but it is not really recommended and possibly unsafe.

Doesn't work!

pan64 · 10-25-2013, 01:26 AM

I have no idea what have you really done, so I cannot help you further....

druuna · 10-25-2013, 01:29 AM

@abhiJ: You mention in your first post that you created a script, but if I look at this "script" it seems that this is not the case, it is a function run from the shell.

You also mention this:

Quote:

this script will accept command line arguments like 'jan' or 'feb' or any name of a month when running via a editor like 'vi'

How does vi come into the picture?

It seems that you are trying to do something the hard way and your posts do not make clear what it is you want/need to do.

Am I right in assuming that you want to extract some information from a database, based on the input given (jan, feb, ...) and store all the output generated in a variable?

If so; What is this variable going to be used for?

abhiJ · 10-25-2013, 02:11 AM

i am just trying to find out if there is a way to pass an argument (which is used to retrieve certain data from a script) to a variable that has been assigned a script???

druuna · 10-25-2013, 02:21 AM

Still not much to go on. I'll give you 2 general examples.

1) Using a script: Create the following script and make it executable:

Code:

#!/bin/bash

[[ $# -eq 0 ]] && echo "No argument passed" && exit 1

echo $1

# add sql code here

Now you can assign the output to a variable in the following way:

Code:

a=$(./script.name.sh jan)
echo "$a"

2) Using a function: Create a file with the following content:

Code:

function unload() {
  [[ $# -eq 0 ]] && echo "No argument passed" && return

  echo $1

  # add sql code here
}

Parse the file to make the function available in the shell:

Code:

. file_name

You can now do the following from the shell:

Code:

a=$(unload feb)
echo "$a"

JJJCR · 10-25-2013, 02:30 AM

check out this simple code below if this is what you want:

Quote:

$x = "String x"

echo "My variable is: $x"

Output:
My variable is: String x

$y = "String y"

echo "This is variable x and y: $x $y"

Output: This is variable x and y: String x String y

check if variable is empty or not:

Quote:

xvar="xx"
if [ -n "$xvar" ]; then
echo "not empty"
else
echo "empty"
fi

output is: not empty
but if you remove "xx" from xvar, of course the output is "empty"

Good luck!!!