topic Re: ksh script needing an interger cmd. line arg in Operating System - HP-UX

ksh script needing an interger cmd. line arg

Marc Ahrendt — Fri, 31 Aug 2001 17:27:49 GMT

what is the best way to test that the 3rd command line argument for my ksh script is a positive interger?

./my_script A B C
C needs to be >=0 and an integer

Re: ksh script needing an interger cmd. line arg

Paula J Frazer-Campbell — Fri, 31 Aug 2001 17:33:25 GMT

Hi

if (( $c >= 0 ))
then

fi

Paula

Re: ksh script needing an interger cmd. line arg

linuxfan — Fri, 31 Aug 2001 17:46:15 GMT

Hi Marc,

you could do something simple like

if [ $3 -gt 0 ]
then
echo "3rd argument greater then 0"
fi

-Ramesh

Re: ksh script needing an interger cmd. line arg

linuxfan — Fri, 31 Aug 2001 17:47:24 GMT

Hi Marc,

for >=0 change it to

if [ $3 -ge 0 ]
then
echo "3rd argument greater then 0"
fi

-Ramesh

Re: ksh script needing an interger cmd. line arg

Sridhar Bhaskarla — Fri, 31 Aug 2001 17:53:05 GMT

First I will see if it is an integer or not

echo "$3 + 1 " |bc 2>&1 |grep syntax > /dev/null
if [ $? = 0 ]
then
echo "Your C is some character"
exit
fi

#Once the above is passed, it means it's an integer. Now I will check to see if it is > 0.

if [ $3 -gt 0 ]
then
echo "C should be greater than 0"
exit 1
fi

...code...

-Sri

Re: ksh script needing an interger cmd. line arg

Sridhar Bhaskarla — Fri, 31 Aug 2001 17:57:52 GMT

ooooopsss.. Small correction.. Friday evening.

yaada..yadaa..yadaaa..
...
if [ $3 -le 0 ]
then
echo "Arg 3 should be greater than 0"
exit
fi

...code...

Re: ksh script needing an interger cmd. line arg

James R. Ferguson — Fri, 31 Aug 2001 19:03:45 GMT

Hi Marc:

Here's one somewhat rigorous way:

#!/usr/bin/sh
#
typeset X=$3
#
[ -z "$X" ] && { echo "no argument provided";exit 2; }
#
[ `expr $X : '[0-9]*'` -ne `expr $X : '.*'` ] && { echo "not a positive integer"
;exit 1; }
#
[ "$X" -le 0 ] && { echo "zero not allowed";exit 1; }
#
echo "OK"
exit 0
#
#.end.

...JRF...

Re: ksh script needing an interger cmd. line arg

Paula J Frazer-Campbell — Fri, 31 Aug 2001 19:15:30 GMT

Hi to all

As I am still learning scripting why use "gt" instead of >= ?

Paula

Re: ksh script needing an interger cmd. line arg

Sridhar Bhaskarla — Fri, 31 Aug 2001 19:20:59 GMT

Doesn't matter with POSIX. I personally commit syntax errors if I try the symbols like instead >= I type in => etc., it's more easy to remember gt, ge etc.

-Sri

Re: ksh script needing an interger cmd. line arg

Marc Ahrendt — Fri, 31 Aug 2001 19:44:15 GMT

thx for everyone's quick replies

sridhar, your solution does not work reliably for all possible input

james, yours works and is more compact than my crude attempt with grep and regular expressions, but i was hoping there was something built into the shell/test like "if (( -I $3 ))" where I would be that magical test on a number

Re: ksh script needing an interger cmd. line arg

Sridhar Bhaskarla — Fri, 31 Aug 2001 20:05:08 GMT

Marc,

Interesting. Did you have any instance where it couldn't get to work?. That will help me rectify my logic.

-Sri

Re: ksh script needing an interger cmd. line arg

Marc Ahrendt — Fri, 31 Aug 2001 20:22:00 GMT

sridhar, below succeeds and f is not an interger
echo "f + 5" | bc 2>&1

Re: ksh script needing an interger cmd. line arg

Sridhar Bhaskarla — Fri, 31 Aug 2001 21:13:45 GMT

Didn't have a system infront of me now. But I know where it would be missing. Try this out.

....
echo "${3}.1 + 1 " |bc 2>&1 |grep syntax > /dev/null
............

if [ $? = 0 ]

....

Thanks for letting me know.

-Sri