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Old 02-27-2007, 02:08 PM   #1
quadmore
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Registered: May 2004
Location: Ottawa, Ontario, Canada
Distribution: Redhat 9
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awk escape character for colon in string


Hello,

I am calling a line of awk from a bash script.

MYSUBSTRING="<factories xmi:type=\"resources.url:URL\" xmi:id=\"URL"
POSITION=`awk -v MYSUBSTRING=$MYSUBSTRING '{ print index ($0, MYSUBSTRING)}' <<< ${line}`
echo $POSITION

awk does not like the colon character in the string. How do I escape it?

Error encountered:
awk: cmd. line:1: xmi:type="resources.url:URL"
awk: cmd. line:1 ^ syntax error


Cheers,
q

Last edited by quadmore; 02-27-2007 at 02:20 PM.
 
Old 02-27-2007, 03:55 PM   #2
wjevans_7d1@yahoo.co
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Registered: Jun 2006
Location: Mariposa
Distribution: Slackware 9.1
Posts: 938

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You gotta buncha stuff to look at here.

First, this is my cut-and-paste of what you said you did, with some echo statements to show what's going on:

Code:
#!/bin/sh

MYSUBSTRING="<factories xmi:type=\"resources.url:URL\" xmi:id=\"URL"
POSITION=`awk -v MYSUBSTRING=$MYSUBSTRING '{ print index ($0, MYSUBSTRING)}' <<< ${line}`

echo x001
echo $MYSUBSTRING
echo x002
echo $POSITION
echo x003
Did I copy it right?

Second, the output I got from running that was this:

Code:
x001
<factories xmi:type="resources.url:URL" xmi:id="URL
x002

x003
Note: no error message at all. Maybe I didn't copy what you did correctly. Please recheck.

Third, what's that $0 doing in there? In a bash command line, $0 is expanded to be the name of the running script if it's in a double quoted or back quoted string; it's left alone if it's in a single quoted string. I think that's what you want here, but you're not getting it. You're getting the name of the program, because this is really part of the back-quoted string; the single quotes within the back-quoted string don't count for squat when bash is interpreting the line; they just get sent through as they are, and bash doesn't even care if it finds an even number of them.

I discovered that by modifying this script somewhat (and saving it as e2, obviously):

Code:
#!/bin/sh

MYSUBSTRING="<factories xmi:type=\"resources.url:URL\" xmi:id=\"URL"
echo x000 "MYSUBSTRING=$MYSUBSTRING '{ print index ($0, MYSUBSTRING)}' <<< ${line}"

POSITION=`awk -v MYSUBSTRING=$MYSUBSTRING '{ print index ($0, MYSUBSTRING)}' <<< ${line}`

echo x001
echo $MYSUBSTRING
echo x002
echo $POSITION
echo x003
... I got this output:

Code:
x000 MYSUBSTRING=<factories xmi:type="resources.url:URL" xmi:id="URL '{ print index (./e2, MYSUBSTRING)}' <<< 
x001
<factories xmi:type="resources.url:URL" xmi:id="URL
x002

x003
See that ./e2 in there?

Anyway, either come back here with comments, or just break it down into simpler pieces so you can see what's going on.

Hope this helps.
 
Old 02-27-2007, 04:56 PM   #3
cfaj
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Registered: Dec 2003
Location: Toronto, Canada
Distribution: Mint, Mandriva
Posts: 221

Rep: Reputation: 31
Quote:
Originally Posted by quadmore
Hello,

I am calling a line of awk from a bash script.

MYSUBSTRING="<factories xmi:type=\"resources.url:URL\" xmi:id=\"URL"
POSITION=`awk -v MYSUBSTRING=$MYSUBSTRING '{ print index ($0, MYSUBSTRING)}' <<< ${line}`
echo $POSITION

awk does not like the colon character in the string. How do I escape it?

Error encountered:
awk: cmd. line:1: xmi:type="resources.url:URL"
awk: cmd. line:1 ^ syntax error


Cheers,
q
Quote shell variables when you use them:

Code:
    POSITION=`awk -v MYSUBSTRING="$MYSUBSTRING" '{...
 
  


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