1. The problem statement, all variables and given/known data:
Making a small GCD calculator. It's fully written, but i'm getting an error that i can't trace.
2. Relevant commands, code, scripts, algorithms:
I'm relatively new to both UNIX and Linux and slightly less new at programming. But I can't figure out why this won't run properly.
It's meant to calculate the GCD of two numbers (simple enough, you'd think). And I designed it myself and it looks good to me and my instructor won't respond. If anyone could help me out, it would be appreciated.
Code:
#! /bin/bash
#Takes arguments to determin the GCD
errorNum="Too many or too few arguments passed."
errorUse="Usage: $0 [decimal] [decimal]"
errorNeg="Cannot use a negative number."
checkIfZero ()
{
if [ $a=0 ]
then
drop=1
elif [ $b=0 ]
then
drop=1
else
drop=0
fi
exit 0
}
if [ $1 < 1 -o $2 < 1 ]
then
echo $errorNeg
echo $errorUse
exit 0
fi
if [ $# -le 1 -o $# -gt 2 ]
then
echo $errorNum
echo $errorUse
exit 0
elif [ $1 -ge 0 ] && [ $2 -ge 0 ]
then
a=$1
b=$2
drop=0
while [ $a -gt 0 ] || [ $b -gt 0 ]
do
if [ $a -gt $b ]
then
if [ drop -gt 0 ]
then
checkIfZero
c=`expr $a % $b`
a=$c
fi
elif [ $b -gt $a ]
then
if [ drop -gt 0 ]
checkIfZero
c=`expr $b % $a`
b=$c
fi
fi
done
if [ $a -gt $b ]
then
echo "The GCD is $a."
else
echo "The GCD is $b."
fi
fi
3. The attempts at a solution (include all code and scripts):
tried set -x and various echo commands to find the problem
[b]4.
AACC, Arnold Maryland, USA, Brandon Brisbon, CSI-135-401:I tried to post the url to the class, but it said i need to post 5 times before i could (sorry)
Hi Friends,
Can any of you explain me about the below line of code?
mn_code=`env|grep "..mn"|awk -F"=" '{print $2}'`
Im not able to understand, what exactly it is doing :confused:
Any help would be useful for me.
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abc
xyz
xyz
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Discussion started by: penchev
3 Replies
LEARN ABOUT CENTOS
escape
escape(1) Mail Avenger 0.8.3 escape(1)NAME
escape - escape shell special characters in a string
SYNOPSIS
escape string
DESCRIPTION
escape prepends a "" character to all shell special characters in string, making it safe to compose a shell command with the result.
EXAMPLES
The following is a contrived example showing how one can unintentionally end up executing the contents of a string:
$ var='; echo gotcha!'
$ eval echo hi $var
hi
gotcha!
$
Using escape, one can avoid executing the contents of $var:
$ eval echo hi `escape "$var"`
hi ; echo gotcha!
$
A less contrived example is passing arguments to Mail Avenger bodytest commands containing possibly unsafe environment variables. For
example, you might write a hypothetical reject_bcc script to reject mail not explicitly addressed to the recipient:
#!/bin/sh
formail -x to -x cc -x resent-to -x resent-cc
| fgrep "$1" > /dev/null
&& exit 0
echo "<$1>.. address does not accept blind carbon copies"
exit 100
To invoke this script, passing it the recipient address as an argument, you would need to put the following in your Mail Avenger rcpt
script:
bodytest reject_bcc `escape "$RECIPIENT"`
SEE ALSO avenger(1),
The Mail Avenger home page: <http://www.mailavenger.org/>.
BUGS
escape is designed for the Bourne shell, which is what Mail Avenger scripts use. escape might or might not work with other shells.
AUTHOR
David Mazieres
Mail Avenger 0.8.3 2012-04-05 escape(1)
10-11-2011
GCD Homework. Untraced error with an "if"
