Find Replace

SimTech has asked for the wisdom of the Perl Monks concerning the following question:

Long time parishioner, finally have a problem that my skills don't have, and a search did not provide a solution... You guys are great... Thanks for the anonymous help.

Have a great many text files... All of which have the pesky ^M for EOL, nothing I can do about that (files are created by an outside program).

I need to search each file, find a match, and replace a word that is two lines below.

Example of text:
__TypeOfAirframe__2_0_Cessna152^M
__StartAltitude__2_0_1200^M
__GearStatus__2_0_Down^M

I want to toggle the gear on all Cessna152s.

For clarity... I used _ as space markers. Imagine the above block is repeated 30 or more times, in hundreds of files. TypeOfAirframe is not always a Cessna, so I don't want to toggle the gear on my 747.

I have had great luck with

perl -pi -e 's/find/replace/g' *.txt

But, I cannot get it to recognize the ^M and spaces to perform a search on the above phrase. HELP?

Comment on Find Replace Download Code

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Re: Find Replace by kennethk (Abbot) on Dec 15, 2011 at 17:00 UTC
`^M` is a carriage return, represented by `\015` or "\r" (less reliably). See Newlines in perlport. You could drop those easily with `s/\r//g`, but for the sake of argument I will assume you want to keep them. They are white space characters, so you can maintain insensitivity to them by ignoring trailing white space, e.g. `/Cessna\d+\s$/`. So you could do this in a one-liner like `perl -pi -e '$i--;$i=2 if /Cessna\d+\s$/;s/Down(?=\s$)/Up/g if !$i' .txt`	[reply] [d/l] [select]
Re^2: Find Replace by SimTech (Initiate) on Dec 15, 2011 at 18:30 UTC
Perfect. The one liner did just the thing Exactly what I needed it to do... But couldn't get the syntax. Thank you so much!	[reply]
Re^3: Find Replace by SimTech (Initiate) on Dec 16, 2011 at 03:43 UTC
Nuts - unpost. Seems I was able to make it work perfectly on a Unix system at the house with a file I made up to resemble the working version. At work on RH Linux - it does not work - as entered as a one line blurp from a command line - it will change all DOWNS to UP. Regardless of the aircraft type. I am reluctant to remove the ^M EOL, only because I have no control over the programs that are reading the files. Back to the drawing board -- thanks again for all the help - if anyone has another suggestion, I'm ready for it! Rob	[reply]
Re^4: Find Replace by graff (Chancellor) on Dec 16, 2011 at 04:08 UTC
Re^4: Find Replace by kennethk (Abbot) on Dec 16, 2011 at 16:12 UTC
Re^2: Find Replace by SimTech (Initiate) on Dec 16, 2011 at 06:23 UTC
Thanks for the link... Very helpful for me. Still getting my butt kicked on the original post, but the link proves good reading.	[reply]
Re: Find Replace by Anonymous Monk on Dec 15, 2011 at 16:47 UTC
But, I cannot get it to recognize the ^M and spaces to perform a search on the above phrase. HELP? You can change the meaning of EOL `perl -l015 -e " s/// "` tells perl to use ^M as EOL `$ perl -le " printf q[CR \r is %03o], ord qq[\r] " CR \r is 015` [download]	[reply] [d/l] [select]
Re^2: Find Replace by SimTech (Initiate) on Dec 16, 2011 at 06:26 UTC
Excuse my ignorance, but will that be a temporary change? Thanks for the tip...	[reply]
Re^3: Find Replace by Anonymous Monk on Dec 16, 2011 at 09:09 UTC
Excuse my ignorance, but will that be a temporary change? Thanks for the tip... No, your bank account will be emptied permanently! :D It is a pair of global variables, perlvar#$\ and perlvar#$/	[reply]