Note that gzip also has an option to provide its result on stdout instead of replacing the file
http://www.mkssoftware.com/docs/man1/gzip.1.asp -c (or --stdout) -- Raul On Sat, Nov 5, 2011 at 12:38 AM, Skip Cave <s...@caveconsulting.com> wrote: > After much experimentation, I finally found a way to expand a .gz > compressed file in J. and put the result in a J variable. > > The first issue I encountered was that I couldn't find the gunzip utility > anywhere. I did find gzip, which, with the right parameters in the command > line (-d for decompress), would unzip my files. However, gzip -d > *replaces*the compressed file with the expanded file, and in any case, > I couldn't > figure out how to easily get the text in the expanded file into a J > variable. > > Ric Sherlock mentioned a program called 7z or 7-Zip. After some more > searching on the web, I found the 7-Zip utility. It can be run from a > command line, and It doesn't replace the compressed file. In fact, it can > put the expanded file wherever you want, most importantly to stdout. > > The next issue was how to execute a command-line utility like 7-Zip from J, > expand the .gz file, and then capture the expanded (text) file in a J > variable. > > Several methods to run command-line tasks were mentioned previously in this > thread, including spawn, fork, shell, and spawn_jtask_. The documentation > was not clear on the differences between all these different verbs, so I > attacked the problem by trial and error. Is there a doc somewhere, that > explains when to use each of these nouns, and the pros and cons of each one? > > In any case, I eventually discovered that the "shell" verb would do what I > wanted. > > First I built a couple of nouns: > The noun 'zipath' contains the path to the command-line 7-Zip utility, with > the utility path enclosed in double quotes, and the control parameters at > the end: > zipath =: '"c:\Program Files (x86)\7-Zip\7z" e -so ' > > The noun 'filepath' contains the path to the compressed file: > filepath =: 'c:\Gzip\log.gz' > > Now this J sentence expands the log.gz file and places the text in a new > variable "log_txt" > log_txt =: shell zipath, filepath > > The only problem with this scheme is that the 7z.exe utility puts verbose > confirmation text in the standard output after the file contents. So every > log_txt file has the following banner at the end of the file: > > file text.... > > 7-Zip 9.22 beta Copyright (c) 1999-2011 Igor Pavlov 2011-04-18 > Processing archive: c:\Gzip\log.gz > Extracting log > Everything is Ok > Size: 272126 > Compressed: 20713 > > I need to figure out how to either supress the banner, throw it away before > putting it in the log_txt file. or ignore it in the next phase. > > My next challenge is to search the log_text file for two different strings > - a "start string" and an "end string". I need to extract any text string > that appears between these two terminator strings. To make matters worse, > there may be multiple start/end terminator string pairs, and I need to > extract each and every string contained between all of the start/end > terminator strings. > > Here's an example of a text file I will be parsing. > > textfile > some stuff > some more stuff > stuff start string good stuff that I want to keep end string other stuff > more stuff > lots of stuff, more stuff, start string more good stuff that I need end > string stuff > bad stuff stuff I don't care about start string even more stuff I want end > string strange stuff > the end > > <<<>>> > > The verb I want will take the textfile in on the right, and return all the > text strings between "start string" and "end string" in the text file. > > So the result of the verb will be: > > good stuff that I want to keep > more good stuff that I need > even more stuff I want > > <<<>>> > > Skip > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
