Shell script to rename file with string from inside file

Question

I have been searching for this in forums and on stackoverflow; it must be here somewhere but I couldn't find it.
I'm on a Mac, using the terminal to run a shell script to rename some pdf files based on file content.

I have a directory full of pdfs that I'm exporting to text files using the opensource pdfbox. The resulting files have the same name as the pdf file but end in .txt. I created the text files so that I could find a string inside the file with the format Page xx Question xx; for example Page 43 Question 2. Given this example, I would like to rename the pdf file as pg43_q2.pdf

I think the regular expression I want is this: /Page\s+(\d+)Question\s+(\d+) but I'm not sure how to read the two captured numbers and save them into a string that I can use as a filename.

The script I have so far is:

#!/bin/sh
PDF_FILE_PATH=$1
echo "Converting pdfs at $PDF_FILE_PATH"

find "$PDF_FILE_PATH" -name '*.pdf' -print0 | while IFS= read -r -d '' filename; do
   echo $filename
   java -jar pdfbox-app-1.6.0.jar ExtractText "$filename" "$filename.txt"
   NEWNAME=$(sed -n -e '/Page/s/Page\s+\(\d+\)\s+Question\s+\(\d+\).*$/pg\1_q\2/p' "$filename.txt")
   echo "Renaming pdf $filename to $NEWNAME"
   # I would do this next but the $NEWNAME is empty
   # mv "filename" "PDF_FILE_PATH$NEWNAME"
done

... but the sed command is not putting anything into the NEWNAME variable.

I'm not particularly attached to sed, any suggestions would be appreciated

Latest edit to script uses the following sed command:

newname=$(sed -nE -e '/Page/s/^.*Page[[:blank:]]+([0-9]+)[[:blank:]]+Question[[:blank:]]+([0-9]+).*$/pg\1_q\2.pdf/p' "$filename.txt")

This works about 50% of the time, but the rest of the time the newname variable is empty when I go to rename the file.

The third line of a converted file that does work:

Unit 2 Review Page 257 Question 9  a)  12 (2)(2)(3)

The third line of a converted file that doesn't work:

Unit 2 Review Page 258 Question 16  a)  (a – 4)(a + 7) = a(a + 7) – 4(a + 7)                             = a2 + 7a – 4a – 28                              = a2 + 3a – 28   b)  (2x + 3)(5x + 2) = 2x(5x + 2) + 3(5x + 2)                                 = 10x2 + 4x + 15x + 6                                 = 10x2 + 19x + 6  c)  (–x + 5)(x + 5) = –x(x + 5) + 5(x + 5)                              = –x2 – 5x + 5x + 25                              = –x2 + 25  d)  (3y + 4)2 = (3y + 4)(3y + 4)                     = 3y(3y + 4) + 4(3y + 4)                     = 9y2 + 12y + 12y + 16                     = 9y2 + 24y + 16  e)  (a – 3b)(4a – b) = a(4a – b) – 3b(4a – b)                                = 4a2 – ab – 12ab + 3b2                                = 4a2 – 13ab + 3b2  f)  (v – 1)(2v2 – 4v – 9) = v(2v2 – 4v – 9) – 1(2v2 – 4v – 9)                                      = 2v3 – 4v2 – 9v – 2v2 + 4v + 9                                      = 2v3 – 6v2 – 5v + 9

shellter · Accepted Answer · 2012-05-24 21:33:12Z

2

Removed unhelpful original answer

echo 'Unit 2 Review Page 257 Question 9  a)  12 (2)(2)(3)'\
| sed -n '/Page/{s/.*Page[ ][ ]*\([0-9][0-9]*\)[ ][ ]*Question[ ][ ]*\([0-9][0-9]*\).*$/pg\1_q\2/;p;q;}'

output

pg257_q9

echo 'Unit 2 Review Page 258 Question 16  a)  (a  4)(a + 7) = a(a + 7)  4(a + 7)'\
| sed -n '/Page/{s/.*Page[ ][ ]*\([0-9][0-9]*\)[ ][ ]*Question[ ][ ]*\([0-9][0-9]*\).*$/pg\1_q\2/;p;q;}'

output

pg258_q16

Otherwise, you had it right!

(Note that the sed processing is the same for both cases).

I've included a trailing ;p;q}, and an initial { so the sed script will just process the line with 'Page' and then quit.

I've expanded the posix char classes to the basic terms, ie [[:digit:]] = [0-9], and replaced the +, with a repetition of the intitial char class followed by the 'zero-or-more' char '*', making [0-9][0-9]*. My personal experience, having learned sed on Sun 3 from OReilly's 2nd edition Sed and Awk (with the comb-binding!), is that all the posix stuff is a distraction and a further source of errors. I'm clearly in the minority on this here on S.O ;-), but I'm willing to admit that newer seds have some great features and in any case .....

I hope this helps.

edited May 24, 2012 at 21:33

answered May 21, 2012 at 17:02

shellter

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9 Comments

GLaDOS Over a year ago

Interesting! Now instead of nothing being returned by sed, on the errant text files I get the correct part plus all the rest of the line. I'm trying to tweak it now to see if I can fix that.

GLaDOS Over a year ago

On my system it's gacking on the negative sign, hex D0, which should be but is not different from the minus sign in the same text). For example the following text segment ...Page 258 Question 16 a) (a – 4)(a + 7) = a(... results in this output: pg258_q16? 4)(a + 7) = a(...

shellter Over a year ago

if you're still using the -E option, that might be causing the problem, but I don't have a mac to test on. Also, my expr [ ] is just [$spaceChar]. right? (You should be able to add $tabChar as well if you want belt-and-suspenders safety from any white-space ;-) Good luck.

shellter Over a year ago

Also, I see hex D0 isn't really a std ascii char. Will take some research. got to go now. Good luck.

GLaDOS Over a year ago

@shelter - Thanks! That gives me an idea for a solution, but I'll have to wait till I get home tonight to try it. Apache pdfbox has a parameter -encoding <output encoding> in which case I should be able to convert the pdfs to ascii only, (crossing my fingers, because there are a lot of unicode characters in the original pdf) which should resolve the problem that sed is having with the converted text. Also, there is a minor typo in the solution you posted, in the first capture: *$[0-9][[0-9]*$ has an extra left bracket. :) so GLaD you keep checking in with me!

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