Com searches through each file named on the command line for the string /*% and takes the rest of the line to be a Unix shell command, which it runs after substituting the file name for any % characters, and the stem (the file name minus the last . and any subsequent characters) for any #'s. For example, if the file junk.c contains the comment
/*% cc -o # % -lm -lmalloc */then com junk.c will run cc -o junk junk.c -lm -lmalloc.
Com stashes its argument list in a file called .comfile, so after running it once, typing com with no arguments will recompile. To include a literal % or # in the command, write %% or ##.