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From: Dominik Vogt <dominik.vogt@gmx.de>
To: Zsh Users <zsh-users@zsh.org>
Subject: Using file lines as "input files"
Date: Fri, 8 Jul 2022 21:58:26 +0100	[thread overview]
Message-ID: <Ysiacl2I2eYF+uY4@gmx.de> (raw)

Okay, there's this script that calculates a checksum on each line
of a file by reading each line and passing it to
cksum/md5sum/shasum etc.

  cat "$INFILE" | while read LINE; do
          echo "$LINE" | cksum

This takes about four minutes on a file with 265,000 lines because
of the program call overhead.


Disclaimer: I _know_ this can be done in seconds with perl /
python, but I like to not rely on scripting languages when the
shell can do the job.


So, would it be possible to pass each line in "$INFILE" as a file
argument to "cksum", i.e.

  $ chksum Fline1 Fline2 Fline3 ... Fline265000

(Of course without actually splitting the input file - the point
is to get rid of the four minute wait, not generating more

And there's this open file escriptor limit of 1024 too.  :-)


Dominik ^_^  ^_^


Dominik Vogt

             reply	other threads:[~2022-07-08 20:59 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-08 20:58 Dominik Vogt [this message]
2022-07-08 21:58 ` Mikael Magnusson
2022-07-08 22:04 ` Bart Schaefer
2022-07-08 23:17   ` Dominik Vogt
2022-07-09  2:21     ` Mikael Magnusson
2022-07-10  0:42       ` Dominik Vogt
2022-07-10  0:45         ` Dominik Vogt
2022-07-10  3:27         ` Bart Schaefer
2022-07-10 17:49           ` Bart Schaefer

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