.Dd July 22, 2021
.Dt WHEN 1
.Os
.Sh NAME
.Nm when
.Nd a simple file watcher
.
.Sh SYNPOSIS
.Nm when
.Op Fl i
.Ar file ...
.
.Sh DESCRIPTION
.Pp
.Nm when
is a simple program that watches any given
.Ar file
for changes.
When the file changes, its name (as specified in the arguments to
.Nm when )
is printed on standard output.
.Pp
If the
.Fl i
argument is provided, an initial such line is printed when the program
starts, before beginning to watch for changes.
.
.Sh ERRORS
.Pp
If one of the watched files is deleted, a message is printed on standard
error and the program exits with error code 1.
.Pp
If a file is renamed, a notice is printed on standard error, but the
program keeps running.
.
.Sh EXAMPLES
.Bd -literal -offset indent
when * | xargs -I% cp % /mnt/usb/
.Ed
.Bd -literal -offset indent
when -i *.ms | while read f; do
	make "${f%.ms}".pdf && kill -HUP mupdf
done
.Ed
.
.Sh AUTHORS
.Pp
.Nm when
is written by
.An John Ankarström Aq Mt "john (at) ankarstrom.se" .