[SOLVED] xxd not doing anything on alpine linux

xxd not doing anything on alpine linux

I'm trying to use xxd to follow a tutorial but it's not printing anything from the Alpine Linux container that I'm trying to run it in.

I am running: xxd -ps -c 1000 <valid-file-path>. When I do this, it just prints out the usage instructions:

~ # xxd -ps -c 1000 $FILE_PATH
BusyBox v1.31.1 () multi-call binary.

Usage: xxd [OPTIONS] [FILE]

Hex dump FILE (or stdin)

    -g N        Bytes per group
    -c N        Bytes per line
    -p      Show only hex bytes, assumes -c30
    -l LENGTH   Show only first LENGTH bytes
    -s OFFSET   Skip OFFSET bytes

I seem to be calling it correctly according to the printed usage instructions. What am I doing wrong?

Solution

Alpine comes with busybox, which is a smaller version of the utilities that come with say, Ubuntu, GNU Coreutils. If you've heard people say "GNU/Linux", this is what they're referring to - many of the utilities you use on the command line were written by the Free Software Foundation.

Busybox xxd doesn't have the -ps option because it was rewritten to be smaller. It prints out the usage instructions because -ps is not valid. If you run this on macos or linux, you'll get different versions of the original xxd.

As you've found, apk add xxd will install this "original" xxd.