Batch convert PNGs to individual PDFs while maintaining deep folder hierarchy in bash

问题

I've found a solution that claims to do one folder, but I have a deep folder hierarchy of sheet music that I'd like to batch convert from png to pdf. What do my solutions look like?

I will run into a further problem down the line, which may complicate things. Maybe I should write a script? (I'm a total n00b fyi)

The "further problem" is that some of my sheet music spans more than one page, so if the script can parse filenames that include "1of2" and "2of2" to be turned into a single pdf, that'd be neat.

What are my options here?

Thank you so much.

回答1:

Updated Answer

As an alternative, the following should be faster (as it does the conversions in parallel) and also able to handle larger numbers of files:

find . -name \*.png -print0 | parallel -0 convert {} {.}.pdf

It uses GNU Parallel which is readily available on Linux/Unix and which can be simply installed on OSX with homebrew using:

brew install parallel

Original Answer (as accepted)

If you have bash version 4 or better, you can use extended globbing to recurse directories and do your job very simply:

First enable extended globbing with:

shopt -s globstar

Then recursively convert PNGs to PDFs:

mogrify -format pdf **/*.png

回答2:

You can loop over png files in a folder hierarchy, and process each one as follows:

find /path/to/your/files -name '*.png' |
while read -r f; do
    g=$(basename "$f" .png).pdf
    your_conversion_program <"$f" >"$g"
done

To merge pdf-s, you could use pdftk. You need to find all pdf files that have a 1of2 and 2of2 in their name, and run pdftk on those:

find /path/to/your/files -name '*1of2*.pdf' |
while read -r f1; do
    f2=${f1/1of2/2of2}                            # name of second file
    ([ -f "$f1" ] && [ -f "$f2" ]) || continue    # check both exist
    g=${f1/1of2//}                                # name of output file
    (! [ -f "$g" ]) || continue                   # if output exists, skip
    pdftk "$f1" "$f2" output "$g"
done

See:

• bash string substitution

回答3:

Regarding a deep folder hierarchy you may use find with -exec option. First you find all the PNGs in every subfolder and convert them to PDF:

find ./ -name \*\.png -exec convert {} {}.pdf \;

You'll get new PDF files with extension ".png.pdf" (image.png would be converted to image.png.pdf for example) To correct extensions you may run find command again but this time with "rename" after -exec option.

find ./ -name \*\.png\.pdf -exec rename s/\.png\.pdf/\.pdf/ {} \;

If you want to delete source PNG files, you may use this command, which deletes all files with ".png" extension recursively in every subfolder:

find ./ -name \*\.png -exec rm {} \;

回答4:

if i understand :

• you want to concatenate all your png files from a deep folders structure into only one single pdf.

so...

1. insure you png are ordered as you want in your folders
2. be aware you can redirect output of a command (say a search one ;) ) to the input of convert, and tell convert to output in one pdf.

General syntax of convert :

convert 1.png 2.png ... global_png.pdf

The following command :

convert `find . -name '*'.png -print` global_png.pdf

• searches for png files in folders from cur_dir
• redirects the output of the command find to the input of convert, this is done by back quoting find command
• converts works and output to pdf file

(this very simple command line works fine only with unspaced filenames, don't miss quoting the wild char, and back quoting the find command ;) )

[edit]Care....

be sure of what you are doing.

if you delete your png files, you will just loose your original sources...

• it might be a very bad practice...
• using convert without any tricky -quality output option could create an enormous pdf file... and you might have to re-convert with -quality "60" for instance...
• so keep your original sources until you do not need them any more

来源：https://stackoverflow.com/questions/38837645/batch-convert-pngs-to-individual-pdfs-while-maintaining-deep-folder-hierarchy-in