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A Unix Utility You Should Know About: Pipe Viewer - good code...

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Saved by 13 people (1 private), first by anonymouse user on 2009-02-02


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Pipe Viewer or pv for short

Highlighted by ognyankulev

It can be inserted into any normal pipeline between two processes to give a visual indication of how quickly data is passing through, how long it has taken, how near to completion it is, and an estimate of how long it will be until completion.

Highlighted by ognyankulev

Another similar example would be to pack the whole directory of files into a compressed tarball:

$ tar -czf - . | pv > out.tgz
 117MB 0:00:55 [2.7MB/s] [>         ]

In this example pv shows just the output rate of “tar -czf” command. Not very interesting and it does not provide information about how much data is left. We need to provide the total size of data we are tarring to pv, it’s done this way:

$ tar -cf - . | pv -s $(du -sb . | awk '{print $1}') | gzip > out.tgz
 253MB 0:00:05 [46.7MB/s] [>     ]  1% ETA 0:04:49

What happens here is we tell tar to create “-c” an archive of all files in current dir “.” (recursively) and output the data to stdout “-f -”. Next we specify the size “-s” to pv of all files in current dir. The “du -sb . | awk ‘{print $1}’” returns number of bytes in current dir, and it gets fed as “-s” parameter to pv. Next we gzip the whole content and output the result to out.tgz file. This way “pv” knows how much data is still left to be processed and shows us that it will totally take 4 mins 49 secs to finish.

Highlighted by farrider

In this example pv shows just the output rate of “tar -czf” command. Not very interesting and it does not provide information about how much data is left. We need to provide the total size of data we are tarring to pv, it’s done this way:

Highlighted by aowongster