Linux pipes

[Giorgos Keramidas]

On Wed, 24 Sep 2008 12:53:29 +0300, Tasos Laskos <tasos.laskos at gmail.com> wrote:
> Christos Ricudis wrote:
>> Ayth h symperifora mporei na allaksei mono ean kaneis dikh sou
>> endiamesh apo8hkeysh twn dedomenwn se kapoio buffer - bebaia gi ayto
>> 8a prepei na grapseis kwdika, kai ta details einai ligo pipa. H
>> logikh panw katw einai h ekshs :
>>
>> declare buffer[MAXLEN]
>>
>> while (not eof())  {
>>    if (write end of pipe is blocking) then {
>>       if (read end of pipe is not blocking and buffer is not full) {
>>          read data into buffer
>>       } else {
>>          block read end of pipe
>>       }
>>      if (write end of pipe is not blocking) then {
>>       if (buffer is not empty) {
>>           feed data from buffer into write end of pipe        } else {
>>          block write end of pipe
>>       }
>>    }
>> }
>>
>> To kalo m'ayth thn me8odo einai oti mporeis na pros8eseis meta polla
>> diakosmhtika features apo ayta poy kanoyn thn pipa apolaysh, opws
>> bandwitdh meter, bandwidth throttling, variable size buffering me
>> jitter detection, ktl ktl ktl.
>>
>> An psakseis sto freshmeat gia "pipe", 8a breis kai merika ergaleia poy
>> kanoun ayth th douleia.
>
> Eyxaristo poly, ayto ksedialine kapos ta pragmata.
> 8a prepei na paikso me to kodika prin to ensomatoso sto vget giati
> omologo pos eimai ligo mperdemenos.

> To poly poly an de katafero na kano ayto pou 8elo 8a valo ena apo ta
> ergaleia apo to freashmeat os dependency kai 8a xrisimopoieio ayto
> anamesa sto vget kai ton ekastote player.

Εναλλακτικά, μπορείς να χρησιμοποιήσεις το universal buffering tool που
έχουν όλα τα UNIX: το dd(1).

        vget [options] PATH | dd ibs=10m obs=4k | lalaki

Ετσι το vget θα μπορεί να γράφει σε batches από 10 MB στο output του,
και το dd θα ταίζει το lalaki με 4 KB chunks.

Το freshmeat έχει ενδιαφέροντα πράγματα, αλλά στη συγκεκριμένη περίπτωση
μάλλον δε χρειάζεται.

> [1] Toses "pipes" stis 10:31am einai kapos.... kapos. Mallon kapoios
> ksypnise me kefakia simera :P

Μην τον ρωτήσεις _πως_ _ακριβώς_ ή _γιατί_ ξύπνησε όμως, γιατί μπορεί να
είναι too much info!