canvon notes

====== Stuff ======

Some miscellaneous stuff that doesn't fit otherwise into [[.:start|the structure]]...

For example, [[#speed_test|speed test by ''timeout'' + ''dd'']], [[#video_file_comparison_using_mpv|video file comparison using mpv]], [[#windows_fork_problems|Windows fork problems]]...


===== Speed test =====

<code>
root@ubuntu:~# timeout --foreground -s INT 60s dd if=/dev/sda bs=4096 of=/dev/null  # ad-hoc USB3 storage speed test...
</code>

The idea is to not measure transfer duration of a fixed size, but to let it run through until a fixed time has passed (and then look at the transfer speed). For this, we wrap the ''dd'' invocation into the ''timeout'' command.

The problem, then, was that ''dd'' didn't output **anything** when run under ''timeout''.

The solution was to use //both// of ''--foreground'' and ''-s INT'' (after the timeout expires, fire signal SIGINT at the wrapped process) //together//. This restored dd's output-at-end, which will now tell the overall transfer speed, as previously expected.


===== Video file comparison using mpv =====

To just get the console output of ''mpv'' where it describes the file played (so we can run a wdiff over the saved outputs of similar files): (Previously, it used to be ''mplayer --identify'' or somesuch.)

<code>
$ mpv --vo=null --ao=null --frames=1 ...
</code>


===== Windows fork problems =====

On Windows (Win32 API), a process can well have threads, but no ''fork()''-without-''exec()'' is possible, as processes are created to be separate (spawn?)...

The CygWin compatibility layer for Linux/UNIX-targetted programs had to work hard to get something similar going: [[https://cygwin.com/cygwin-ug-net/highlights.html#ov-hi-process|CygWin highlights: Process Creation]] (via [[http://blog.rolpdog.com/2020/03/why-no-ansible-controller-for-windows.html|ansible controller heavy user of fork() without exec()]])
canvon notes

User Tools

Site Tools

Page Tools
