SLOWBAUD(1)                    Urchlay's Useless Stuff                    SLOWBAUD(1)

NAME
       slowbaud - simulate a low bitrate serial connection

SYNOPSIS
       slowbaud [<bits-per-sec>] [<file> ...]

       slowbaud [<bits-per-sec>] -c [<command> [<arg> ...]]

       slowbaud [<bits-per-sec>] -e <string> [<string> ...]

       slowbaud [<bits-per-sec>] -b [<bytes>]

DESCRIPTION
       slowbaud  by  default  acts  as a filter, or like the cat(1) command. It reads
       files or its standard input, and writes the contents  unmodified  to  standard
       output... but slowly, at the given bits-per-second rate.  Input and output are
       unbuffered.

       slowbaud can also act like echo(1) (the -e option), or run an interactive com‐
       mand in a pseudo-tty (the -c option).

       The  <bits-per-sec> argument is optional. If it's not given, the bit rate will
       be set from SLOWBAUD_BPS in the environment, or a built-in default of 2400  if
       that's not set.

OPTIONS
       bits-per-sec
              The  bit  ("baud") rate to simulate. Range is 1 to 500000. This must be
              the first argument. slowbaud assumes that if the first  argument  is  a
              number,  it's  the  bit  rate. If you're trying to pass a filename that
              consists only of digits, give -- as the first  argument,  or  use  e.g.
              ./filename.

       -e     Echo mode. Prints all further arguments as strings to stdout, separated
              by a single space, at the  given  bit  rate.  Does  not  support  back‐
              slash-escapes,  or  any  of the options of the regular echo command. At
              least one argument is required after -e.

       -c     Command mode. Next argument (if present) is the  command  to  run,  any
              remaining  arguments become arguments to the command. With no arguments
              after -c, a shell is spawned.  This creates a pseudo-tty, so  the  com‐
              mand can be interactive.

       -b     Benchmark  mode. Prints <bytes> (or 4096, if no <bytes> given) bytes of
              zeroes to /dev/null. Mostly useful for development and troubleshooting.

       -h, -? Show built-in help message and exit.

ENVIRONMENT
       SLOWBAUD_BPS
              Can be used to set the bit rate, when  no  <bits-per-sec>  argument  is
              used.

       SLOWBAUD_DEBUG
              Set  this (to any value) in the environment to see verbose debug output
              on stderr, including timing accuracy stats.

       SHELL  Standard *nix environment variable, used to determine what shell to run
              when -c is given with no <command>. If unset, /bin/sh is used.

EXIT STATUS
       Without  -c  or  -e,  0  for  success,  non-zero on any error such as nonexis‐
       tent/unreadable files. slowbaud exits immediately  on  such  errors  (this  is
       unlike cat(1)).

       With -e, exit status is 0, unless there were no arguments to echo.

       With -c, exit status is that of the child process, or 127 if the child process
       couldn't be spawned (e.g. command not found).  Of course,  the  child  process
       could also exit with status 127...

       With -b, exit status is 0, unless something catastrophic happened (e.g. unable
       to open /dev/null for writing).

NOTES
       The timing inaccuracy will almost always result in the bitrate being  slightly
       too slow.

       We  can't  really insert a delay between the bits of a byte, since I/O is done
       with byte granularity. For calculation purposes, <bits-per-sec> is divided  by
       10  to  get  bytes  per  second. This simulates "8-N-1": one start bit, 8 data
       bits, no parity, and 1 stop bit (total of 10 bits per byte).

BUGS
       With -c, signals aren't handled gracefully.  Window  size  changes  (SIGWINCH)
       don't  get  propagated to the child process, and pressing ^C doesn't interrupt
       the process until all pending output is processed.

COPYRIGHT
       slowbaud is copyright 2021, B. Watson <yalhcru@gmail.com>. Released under  the
       WTFPL. See http://www.wtfpl.net/txt/copying/ for details.

0.0.1                                 2021-07-24                          SLOWBAUD(1)