xbmtopbm
Convert X11 or X10 bitmap to PBM format
TLDR
Convert XBM to PBM
$ xbmtopbm [input.xbm] > [output.pbm]
SYNOPSIS
xbmtopbm [file]
DESCRIPTION
xbmtopbm reads an X11 or X10 bitmap (.xbm) as input and produces a PBM image as output. X bitmap files are C source code that define image data as arrays; this tool extracts and converts the image data. Part of the Netpbm toolkit.
INSTALL
sudo apt install netpbm
sudo dnf install netpbm
sudo pacman -S netpbm
sudo apk add netpbm
sudo zypper install netpbm
brew install netpbm
nix profile install nixpkgs#netpbm