regular expression help needed

laoisfan · 12-12-2005 03:06PM #1

hi

i am using ksh in unix. i have set an environmental variable, X, to the following:

[INDENT]
# echo $X
java full version "1.5.0_06-b03"
[/INDENT]

i am trying to do a simple check (using regular expression) in awk to see if X contains "1.5.0". i just need to know yes or no i.e. 0 for yes or >0 for no. i am doing the following:

[INDENT]
# echo $X | awk '$4 ~ /1.5.0/'
java full version "1.5.0_06-b03"
# 
[/INDENT]

as you can see, the awk prints the entire sting out if it does contain 1.5.0. if you check for 1.4.2 it does not print anything. in all cases, exit code is 0.

is the another way i can use a regular expression i.e. awk, nawk or sed and just check the exit code for a yes or no answer? not doing this in perl (would prefer to but am not).

--laoisfan

laoisfan · 12-12-2005 03:11PM

just another thought, if not possible to check for 0 or >0, would it be possible to print out the 1.5.0 if X does contain 1.5.0 i.e print 1.5.0 not 1.5.0_06-b03.

any takers?

laoisfan · 12-12-2005 03:32PM

am looking at the index function with awk.....

Zombrex · 12-12-2005 03:43PM

its possible afaik to check if the value returned was true of false

this might help
http://www.unix.org.ua/orelly/unix/ksh/ch06_02.htm

laoisfan · 12-12-2005 03:57PM

i have checked the return value and it is always 0 unless i am doing something wrong.

at the moment i am looking at using index with awk. it returns 0 if no index is found else it returns a positiva number i.e. the value at which the index of the string your looking for starts in the main string.

running into a wee problem with awk at the moment, hopefully that will be sorted soon....

laoisfan · 12-12-2005 04:18PM

Using the following which seems to do what I need

[INDENT]
awk 'BEGIN {print index("abc 1.5.0-06-b05","1.5.0") }'
3 <---- if i keep hitting return it keeps printing 3...never
returns to command prompt unless i control-c!!
[/INDENT]

anyone?

daymobrew · 13-12-2005 01:00AM

This spat out the right answer for me

#!/bin/bash

export X="java full version \"1.5.0_06-b03\""
echo "\$X = $X"

# Test if anything returned by grep.
if [ -n "`echo $X | awk '{print $4}' | grep \"1\.5\.0\"`" ]
then
  echo "\$X has 1.5.0."
else
  echo "No 1.5.0 found."
fi

regular expression help needed

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