can some elaborate the difference between sysread/read sysseek/seek

lightoverhead has asked for the wisdom of the Perl Monks concerning the following question:

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Re: can some elaborate the difference between sysread/read sysseek/seek by davido (Cardinal) on Sep 26, 2013 at 20:21 UTC
See also read and sysread. Dave	[reply]
Re: can some elaborate the difference between sysread/read sysseek/seek by wjw (Priest) on Sep 26, 2013 at 19:40 UTC
Have never used either, but the way I read the docs sysseek and sysread implies that one (seek) gets you to a place in the file measured in position units(unicode or bytes) and returns success or not, and the other (read) reads from that place for some length in position units(unicode or bytes). So one gets you to where you want to start, and the other returns scalar data from the start position up to the length you ask for... Hope that is helpful... ...the majority is always wrong, and always the last to know about it... ..by my will, and by will alone.. I set my mind in motion	[reply]
Re^2: can some elaborate the difference between sysread/read sysseek/seek by Marshall (Canon) on Sep 27, 2013 at 04:29 UTC
sysread() is normally used for very low level I/O. Normally in Perl, you shouldn't be doing that. This is possible, but there are buffering complications. read() and seek() are much more normal. Do not mix read, seek or sysread and sysseek together.	[reply]
Re: can some elaborate the difference between sysread/read sysseek/seek by ikegami (Patriarch) on Sep 27, 2013 at 13:11 UTC
`sysread` doesn't buffer. `read` buffers. On the rare occasions you need unbuffered IO (e.g. you want to use `select`), you need to use `sysread` and `sysseek`. (As such, `sysread` will always return as soon as data is available, if is there is data available than requested.) The rest of the time, you want to use `read` and `seek`.	[reply] [d/l] [select]
Re: can some elaborate the difference between sysread/read sysseek/seek by vsespb (Chaplain) on Sep 27, 2013 at 13:19 UTC
sysread could also returns errors like EINTR.	[reply]