From time to time you come upon some useful oneliner in the shell. Either because you see it somewhere, see someone doing it, or because you need it and produce one yourself. And most of the time, it’s not enough to put into a shell-script, so you find yourself hunting for it in your .bash_history. Well, here are some: <\/p>\n
Do something to a lot of files<\/strong> You’ll need this a lot. Does not work with files containing spaces <\/p>\n Convert a load of images<\/strong> Make pdf out of a several images<\/strong> You really want to set the limits, unless you have more RAM than the whole images converted to pbm.<\/p>\n With Graphicsmagick, you need to set a compression for jpg, otherwise the resulting PDF will be huge.<\/p>\n The resources you want to give those programs can be set using environment-variables: <\/p>\n Make pdf out of a lot<\/em> of images<\/strong> Change resolution (DPI) of an image<\/strong> split\/crop pictures<\/strong> Note that this does not really crop the image, but splits it into as many parts as necessary, using “target” as prefix, adding a number as suffix. <\/p>\n fix offset<\/strong> Lately, “crop” seems to behave differently, it leaves all but the first part with an offset. This makes the picture disappear in gimp, and stretched if you make a pdf out of it. That’s why you may need to repage. <\/p>\n rotate<\/strong> rotates 90 degrees clockwise. <\/p>\n Attach pictures to each other, one below the other<\/strong> Important is that width and height are the dimensions of each of the sources. For putting them next to each other, just use 2×1 as tile. <\/p>\n Rename files according a textfile-list<\/strong> Delete empty directories<\/strong> Remove first page of a PDF<\/strong> Yes, pdftks syntax is a bit alien. <\/p>\n Merge PDFs<\/strong> Unpack lots of packed files into different directories<\/strong> If you have a load of packed files, in this case rar, and you want to unpack each into a different subdirectory, according to the name of the rar-file. <\/p>\n Get rid of magnatune-advertisements in mp3s<\/strong><\/p>\n Merge AVI-movies<\/strong> That’s the basic way. If you want to process a whole directory with avi-files whose filenames have a distinct part (like “cd≶num>” or “-Part≶num>” as in my example) you can do something this:<\/p>\n
\nfor i in *; do command $i; done<\/code><\/p>\n
\nfor i in *.tif; do convert -quality 75 $i `basename $i .tif`.jpeg;<\/code><\/p>\n
\nconvert -limit memory 32 -limit map 32 *.png target.pdf<\/code><\/p>\ngm convert -compress JPEG *.jpg target.pdf<\/code><\/p>\nexport MAGICK_MEMORY_LIMIT=\"640mb\"
\nexport MAGICK_MAP_LIMIT=\"320mb\"
\nexport MAGICK_AREA_LIMIT=\"640mb\"<\/code><\/p>\n
\nBut the whole idea of using ImageMagick or GraphicsMagick to create pdf-files is very much flawed, since both first convert the jpeg-files into an raw, uncompressed intermediate format which tends to eat up all available memory, and then crash. And which is completely nonsensical too, since jpeg-files can be embedded into pdf as they are. Luckily, pdfjoin will help us, tough it accepts only files with the extension ‘.pdf’ as input as of yet: <\/p>\nmmv '*.jpg' '#1.pdf'; pdfjoin --outfile target.pdf *.pdf<\/code><\/p>\n
\nconvert -density 600 -units PixelsPerInch source.png target.png<\/code><\/p>\n
\nconvert -crop 1230x880 source.png target<\/code><\/p>\n
\nconvert +repage source.png target<\/code><\/p>\n
\nconvert -rotate 90 source.png target<\/code><\/p>\n
\nmontage +frame +shadow +label -tile 1x2 -geometry \"widthxheight+0+0\" source1.png source2.png target.png<\/code><\/p>\n
\nfor i in `cat list` ; do mv `echo $i | awk -F\"-\" '{print $1\".ext\"}'` $i.ext ; done<\/code><\/p>\n
\nfind . -type d -empty -depth -exec rmdir {} \\;<\/code><\/p>\n
\npdftk A=source.pdf cat A2-end output target.pdf<\/code><\/p>\n
\npdftk sources*.pdf cat output target.pdf<\/code><\/p>\n
\nfor i in *.rar; do mkdir `basename $i .rar`; mv $i `basename $i .rar`; cd `basename $i .rar`; rar x $i; cd ..; done <\/code><\/p>\nfor i in *.mp3; do mp3splt -s -p min=2 -d `basename $i .mp3` $i ; done<\/code><\/p>\n
\nmencoder -forceidx -oac copy -ovc copy -o outputfile.avi parts*.avi<\/code><\/p>\n