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Regular Expressions in shell scripts <yawn>

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# 1  
Old 09-04-2001
Regular Expressions in shell scripts <yawn>

Quite possibly a simple problem who's answer is evading me:

I am trying to write a sh shell script, part of which is *logically* trying to do the following:

if [ $1 = [A-Za-z] ]; then

if [ $1 = [0-9.] ]; then

Where the 1st condition is looking for a hostname passed as $1, the second a dotted-quad ip address, and the 3rd a catch-all error condition.

I cannot work out how to use regex with the test ([) command. Would $1 always evaluate to "TRUE"? And therefore I would use something like:

if [ $1 -a regex ]; then

or not?
BTW: I know the regex I have given in the example are not water-tight for their application ([0-9.] doesn't necessarily guarantee a dotted-quad by any means), this is a tool which is only going to be used by myself, and therefore isn't too much of a problem

If someone would like to supply the regex for a dotted quad I would be most greatful :-), but no sweat.

Thanks in advance.
# 2  
Old 09-04-2001
Dotted Quad regex

Is this the correct regex for a dotted-quad IP address?

# 3  
Old 09-04-2001
In ksh you can use patterns...
if [[ $1 = +([0-9]).+([0-9]).+([0-9]).+([0-9]) ]] ; then
   echo $1 is an ip address
   echo $1 is not an ip address

# 4  
Old 09-04-2001
stright from Mastering Regular Expresstions by Oreilly page 124


this should all be on 1 line btw. the reason 0-9 wont work as mentioned above it cuz if you want a ligit ip all the time 0-9 wont work. remember 0-9 says even an ip of 999.999.999.999 is valid when we all know is not valid in any universe (yet anyways).

btw this book is a book i think everyone that is into unix, programing, scripting should read.

the hostname check is on page 167

Last edited by Optimus_P; 09-04-2001 at 07:38 PM..

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