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.. RST source for slowbaud(1) man page. Convert with:
.. rst2man.py slowbaud.rst > slowbaud.1
.. rst2man.py comes from the SBo development/docutils package.
.. Note: if you edit this, run "make" to recreate the man page and README,
.. *then* do a "git commit -a". Even though they're generated files, the man
.. page and README.txt are tracked by git.
.. |version| replace:: 0.0.1
.. |date| date::
========
slowbaud
========
----------------------------------------
simulate a low bitrate serial connection
----------------------------------------
:Manual section: 1
:Manual group: Urchlay's Useless Stuff
:Date: |date|
:Version: |version|
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 command 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 backslash-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 command 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
nonexistent/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.
|
