Convert a PNM or PAM file into a Motif UIL icon file. More information: https://netpbm.sourceforge.net/doc/pamtouil.html.
pamtouil path/to/input.pnm|pam > path/to/output.uil
pamtouil -name uilname path/to/input.pnm|pam > path/to/output.uil