gcfdp

#!/bin/bash
## Simple shell script to gen cover.jpg for djvu and pdf files
## It is assumed that each file is located in its own folder.
## Files and folders names must not contain special symbols like [] and so on
## Uses: find, wc, head, tail, sed, ddjvu, cjpeg, gs
## No any checks so fails are possible.
## Author Andrew S. [github,gitlab].com/quarkscript/ Licence GPL

list=$(mktemp XXXXXXX.tmp)

## gen covers from djvus
find -name *.[Dd][Jj][Vv][Uu] | sed 's@\.\/@@g' >$list
find -name *.[Dd][Jj][Vv] | sed 's@\.\/@@g' >>$list
for ((jj=1;jj<=$(wc -l $list | sed "s/ $list//g");jj+=1)); do
    fileis=$(head -n $jj $list 2>&1 | tail -n 1)
    filename=$(echo $fileis | sed 's@.*\/@@g')
    dirname=$(echo $fileis | sed "s@\/$filename@@g")
    if [ ! -f "$dirname/cover.jpg" ]; then
        ddjvu -format=ppm -page=1 "$fileis" "$dirname/cover.ppm"
        cjpeg "$dirname/cover.ppm" > "$dirname/cover.jpg"
        rm -f "$dirname/cover.ppm"
    fi
done

## gen covers from pdf
find -name *.[Pp][Dd][Ff] | sed 's@\.\/@@g' >$list
for ((jj=1;jj<=$(wc -l $list | sed "s/ $list//g");jj+=1)); do
    fileis=$(head -n $jj $list 2>&1 | tail -n 1)
    filename=$(echo $fileis | sed 's@.*\/@@g')
    dirname=$(echo $fileis | sed "s@\/$filename@@g")
    if [ ! -f "$dirname/cover.jpg" ]; then
        gs -dNOPAUSE -dBATCH -dSAFER -sDEVICE=jpeg -sPageList=1 -sOutputFile="$dirname/cover.jpg" "$fileis"
    fi
done

rm -f $list