.TH CHN 1df "January 2017" "Manual page for chn"
.SH NAME
.B chn
\- filter standard input through multiple runs of a command
.SH USAGE
.B chn
COUNT
COMMAND [ARG1...]
.SH DESCRIPTION
Run the given command the specified number of times, passing the standard
output of each run into the standard input of the next.
.P
As an example, to quote some text with quo(1df) repeatedly:
.P
    $ cat msg
    Hello!
    $ chn 2 quo < msg
    >> Hello!
    $ chn 5 quo < msg
    >>>> Hello!
.P
Zero is a valid count; in this case the input is passed untouched to output:
.P
    $ chn 0 quo < msg
    Hello!
.P
Don't confuse this with simply repeating a command. This happens to work:
.P
    $ chn 5 sync
.P
But this will not do what you expect:
.P
    $ chn 5 echo foo
.SH CAVEATS
It's slow.
.P
It's not a real pipe. The commands are run successively, not in parallel. That
means you can't pass one line to it and have it return another line before
sending EOF, for unbuffered (e.g. linewise) tools.
.P
There's almost certainly a better way to do this, fixing one or both of the
above issues, and possibly even in shell; maybe with curlier file descriptor
logic to save unneeded open(2) syscalls. I smell `eval` usage on the horizon.
.SH SEE ALSO
maybe(1df), try(1df)
.SH AUTHOR
Tom Ryder <tom@sanctum.geek.nz>