When sorting numbers, you can use either -g or -n. I've noticed that Linux users without Unix experience tend to use -g, while old Unix folk are often unaware of that flag at all and continue to use -n. There is a difference between the two flags, although "man sort" doesn't explain it - "info sort" does a better job.
For ordinary numbers, -g and -n are identical, and although -g is slower, for small input sets it really doesn't matter. But when you mix in scientific notation, -n does not work:
$ cat t 123 12 11 9 453 99 10e1 10e0 101 1 8.95 $ sort -n t 1 8.95 9 10e0 10e1 11 12 99 101 123 453 $ sort -g t 1 8.95 9 10e0 11 12 99 10e1 101 123 453
I mentioned that "sort -g" is slower. That's because it calls "strtod" to convert to double-precision floating point. When -n is used, sort simply aligns decimal points (real or assumed) and then does an ordinary string comparison. That's much faster, but of course it fails to handle scientific notation. The "faster" is, as noted, usually unimportant:
$ wc -l t 1321 t $ time sort -g t > /dev/null real 0m0.013s user 0m0.012s sys 0m0.002s $ time sort -n t > /dev/null real 0m0.009s user 0m0.008s sys 0m0.001s
You may have "-g" even if your man page doesn't mention it: my Mac OS X Tiger has -g but the man page doesn't mention it.
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More Articles by Tony Lawrence © 2013-06-14 Tony Lawrence
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Tue Apr 21 12:23:30 2009: 6247 TonyLawrence
I noticed this morning that I can no longer use "sort +2" (well, you CAN, but you have to work at it) on OS X
The "man" page doesn't mention the old "+" syntax but "info sort" still does.
(link) explains:
On older systems, sort supports an obsolete origin-zero syntax ‘+pos1 [-pos2]’ for specifying sort keys. This obsolete behavior can be enabled or disabled with the _POSIX2_VERSION environment variable (see Standards conformance); it can also be enabled when POSIXLY_CORRECT is not set by using the obsolete syntax with ‘-pos2’ present.
Fri Jun 14 02:16:16 2013: 12121 KanthaRao
Hi this is a very old post, nevertheless a good mention for the differences between -g and -n sort. I am using another command which is something like "sort +4g". It will sort out based column 4 smallest to largest.
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sort -g vs. sort -n Copyright © May 2005 Tony Lawrence
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