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May 11, 2006 8:11 AM

I need, post haste, a perl or shell script that will loop through a directory and combine files. The files are named like this: 212_Class001, 212_Class002, 212_Class0** There are some gaps in the sequence. In retrospect it was a bad idea to store class notes in individual files. I'd like to combine them in the sequence they are numbered. Can someone please help ‽
posted by Grod to Education (10 answers total)

ls | sort | xargs cat > result-file-name.txt

in the directory you've got your notes in seems like it ought to work. This is assuming they're stored on a computer that's sufficiently unixy.
posted by jacobm at 8:18 AM on May 11, 2006

Best answer: at a shell prompt, all you need to do is:

cat 212_Class0?? > 212_Class_Notes

That will concatenate all 212_Class0* files, in order, into 212_Class_Notes
posted by aerosolkid at 8:20 AM on May 11, 2006

Response by poster: Damn, I forgot to say, there are other files in there, too, like 235_Class0** and 206_Class0** and *.pdf and so on, I want to isolate the 212 notes. And the system is GNU/Linux, so that should work.
posted by Grod at 8:21 AM on May 11, 2006

Response by poster: aerosolkid, perfect thank you! one of these days I really need to sit down and learn how to use all those powerful little tools.
posted by Grod at 8:22 AM on May 11, 2006

Best answer: aerosolkid's solution will work too --- or, between the ls and the sort in my pipeline, stick in grep '212_Class':

ls | grep '212_Class' | sort | xargs cat > outputfile.txt
posted by jacobm at 8:25 AM on May 11, 2006

Response by poster: Cool, what if I wanted to insert two line breaks between the end of one file and the beginning of another?
posted by Grod at 8:31 AM on May 11, 2006

Response by poster: Great, thanks! I'm off to study for twenty minutes and then fail an exam. I hope I don't abuse the apostrophe like I did in the title of this post, Matt, could you maybe fix that for me, it's embarrassing.
posted by Grod at 8:36 AM on May 11, 2006

I would just go to a full-blown for loop (this is bash-specific now, by the way) and do:

for f in `ls | grep '212_Class' | sort`; do cat $f; echo ""; done

That echo "" will get inserted after every file, so you can change it to whatever you want.
posted by jacobm at 8:43 AM on May 11, 2006

"ls | grep" makes no sense. Why not just use the right glob wildcard? And the wildcard expansion will be sorted already.

for F in 212_Class0??; do cat $F; echo; done
posted by Rhomboid at 11:21 AM on May 11, 2006

Good point, Rhomboid. I think this just reflects my personal tastes in these things --- I tend to always use grep rather than wildcards, because it's more powerful in general, and I like to make my sorts explicit rather than relying on the details of the expansion. (I tend to always want things very explicit --- c.f. echo "" rather than echo.)
posted by jacobm at 11:39 AM on May 11, 2006