The open/close operations can be limited if we simply use this instead, so writes can be done more efficiently (option B):
Also reads can be optimized in shell by reading the files at once (option C):
Since there is only 1 variable per line we can do it like this, otherwise we would need to adjust IFS.
Also the shell used can have quite an impact. I did some speed test with files with 32 lines each with methods A, B and C. I tested with bash, ksh93 and dash.
Also I used Pludi's perl script of this thread (without the system date calls) and the following awk script for comparison:
These are the results (time in seconds):
bash
dash
ksh93
perl
awk
A
line by line
60,34
10,67
14,69
B
line by line
50,93
8,14
8,09
0,87
C
read into memory
31,23
5,50
7,50
1,55
Quote:
Originally Posted by pludi
[..] Each call to printf costs the time of a process spawn. And the file has to be opened, written, and closed on each call.
printf is a shell builtin, so in this case no spawn is needed...
Last edited by Scrutinizer; 02-27-2011 at 11:40 AM..
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