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Old 06-07-2004, 11:31 AM   #1
Registered: Jan 2004
Location: Pakistan
Distribution: OpenSuse 10.2, Slackware 11, Solaris 10
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Bash scripting questions

Hi all,

I have a few bash scripting questions:

How do I return a value from BASH script to a C++ Program?

I have a few problem with this script:

#! /bin/bash
# This file creates a swapfile
# Version: 0.1 07/6/04
# Author:
echo "Please enter the size of the swapfile (in MB)"
read SIZE
echo "Please Enter the path where the swapfile is to be created along with file name?"
read PATH

dd if=/dev/zero of=$PATH bs=1024 count=$(SIZE*1024)
mkswap $PATH $SIZE
echo "Swap File has been created at $(PATH) of $(SIZE),"
echo "to use swapfile use"
echo " swapon path_to_Swapfile"
echo "to disable"
echo " swapoff path_to_swapfile"
echo "Append an entry to /etc/rc.d/rc.local to automatically enable swapfile at startup"

I get the following errors:
./ line 1: SIZE*1024: command not found
./ line 15: dd: command not found
./ line 16: mkswap: command not found
./ line 17: sync: command not found
./ line 1: PATH: command not found
./ line 1: SIZE: command not found
Old 06-07-2004, 11:58 AM   #2
LQ Guru
Registered: Feb 2003
Location: Colorado Springs, CO
Distribution: Gentoo
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Not sure, but I think you need double-parentheses around the arithmetic stuff: $((SIZE*1024)). Also, $(PATH) should be just $PATH, $(SIZE) should be just $SIZE.
Old 06-07-2004, 12:13 PM   #3
jim mcnamara
Registered: May 2002
Posts: 964

Rep: Reputation: 36
The other issue: when you exec a process like this, you no may longer have environment variables like PATH.

So, fully qualify each command and define PATH:
# examples - the paths may not be correct for
# your box 
let SIZE=SIZE*1024
/usr/bin/dd if=/dev/zero of=$PATH bs=1024 
/usr/sbin/mkswap $PATH $SIZE


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