test for integer

[ReeKetta]

Is there a way to check to see if the user entered variable is a valid integer?

I have:

...
read var
if test $var -lt 5
then
echo "integer"
fi

This works just fine if var is an integer, but if it is not, then I get a "bad integer" error. I would like it to not give an error, if that is possible.

Thanks for the help.

 

[bigoldbulldog]

This awk script may help... But is doesn't deal with exponents. It expects only the number (or one per line) and returns T or F.

BEGIN {
sign = "[+-]?"
integer = "[0-9]+"
ws = "[ ]*"
number = "^" ws sign integer ws "$"
}
{
printf ("%s\n", ($0 ~ number) ? "T" : "F&quot
}

Cheers,
ND

 

[vgersh99]

if on Solaris, "man ckstr"

Ex:

ckstr -Q -r "[-+]*[0-9][0-9]*[eE]*[-]*[0-9]*" -p "Input number: "

 

[StevetheBlue]

Using ksh try:

read n
if [ ! -n "$n" -o -n "$(echo $n | sed 's/[0-9]//g')" ]; then
echo "It is not a number"
else
echo "It is a number"
fi

Steve.