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UNIX for Dummies Questions & Answers

First argument is numeric or not

 
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# 1  
Old 10-21-2008
First argument is numeric or not
Hi everyone, I want my script to check if the first argument has only numbers or not. Im not sure what im doing wrong.

This is how it looks like:

if [ $1 = ( grep "[^0-9]*") ]
then
echo 'The first arguement should only be in numeric' 1>&2
exit 1
else
exit 0
fi
# 2  
Old 10-21-2008
Hammer & Screwdriver Take a look at the following
Code:
> tst_val="12345"
> if [ $tst_val = `echo $tst_val | tr -d "[:alpha:]"` ]; then echo "all numbers";  else echo "Not just numbers"; fi
all numbers
> tst_val="12345a"
> if [ $tst_val = `echo $tst_val | tr -d "[:alpha:]"` ]; then echo "all numbers";  else echo "Not just numbers"; fi
Not just numbers
>

# 3  
Old 10-21-2008
I don't fully understand what the above sample script you have provided but I have modified mine so it looks like this but it has some errors.

I would appreciate if someone can fix it for me.

Thanks


if [ $1 = "echo $1 | grep "[^0-9]*" ]
then
echo 'The first arguement should only be in numbers' 1>&2
exit 1
else
exit 0
fi

if [ $2 = "echo $2 | grep "[^a-zA-Z]*" ]
then
echo 'The second arguement should only contain letters' 1>&2
exit 1
else
exit 0
fi
# 4  
Old 10-21-2008
You can also use a case statement to test the input i.e.
Code:
#!/usr/bin/bash

case $1 in
    *[!0-9]* )  echo "$1 is not all numeric" && exit 1;;
esac

exit 0

# 5  
Old 10-21-2008
Quote:
Originally Posted by darkhider
Hi everyone, I want my script to check if the first argument has only numbers or not...
if [ $1 = ( grep "[^0-9]*") ]
then
...
It might be easier if you use extended grep - egrep,

Code:
if  echo  "$1"  | egrep "^[0-9]+$"
 then
   echo "The first argument is numeric"
 else
...

Last edited by rubin; 10-21-2008 at 07:44 PM..
# 6  
Old 10-21-2008
Okay, I have another question. This script that i am trying to make is about the find command. The 1st variable is the size and the 2nd variable is the directory.

So for example the user inputs the directory name but that directory name actually doesnt exist, how can I tell the script to tell the user that "the directory that you specified doesnt exist"?
# 7  
Old 10-21-2008
Code:
[ -d "$2" ] && echo "dir found" || echo "dir not found"

man bash or google "bash scripting manual" and the first hit will teach you much more.
 
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