Ah, finally: no more of
for i in 1 2 3 4 5 6 7 8 9 0 do .. whatever done
With Bash 3.0, we now have brace expansion for lists:
for i in {1..10} do echo $i done
And, happily:
for i in {10..1} do echo $i done
Prior to this, we sometimes used "seq", which could result in such awful things as:
for i in `seq 65 69`; do echo -e `printf '\\%03o' $i`; done
Ugly. The Bash 3.0 way is so much cleaner:
for i in {A..E}; do echo $i;done
This also works for more traditional brace expansion use:
$ echo foo{1..4}bar foo1bar foo2bar foo3bar foo4bar # used to be done as $ echo foo{1,2,3,4}bar foo1bar foo2bar foo3bar foo4bar
Nesting of course still works:
echo foo{bar{1..3},-is-done} foobar1 foobar2 foobar3 foo-is-done
and you can use it for such tasks as:
mkdir {A..D}{1..3}{0..9}
which would have required nested loops before Bash 3.0.
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More Articles by Tony Lawrence © 2010-11-02 Tony Lawrence
I was taught that the human brain was the crowning glory of evolution so far, but I think it’s a very poor scheme for survival (Kurt Vonnegut).
Mon Oct 3 07:31:46 2005: 1149 drag
Oh.. that's nice. (I am sure somebody will come along and point out that ksh or other 'alternative' shell had it first, but still this is cool) :P
Mon Oct 3 13:09:30 2005: 1151 infinity
never knew that this kind of facility was available.
thanks!
Mon Oct 3 13:20:49 2005: 1152 TonyLawrence
Well, nested brace expansion has worked before now, but the list expansion in braces is new. Combining both is pretty darn powerful as you see above..
Wed Apr 15 14:24:41 2009: 6177 anonymous
Hi,
Is there anyway to specify an increment in the brace expansion?
Wed Apr 15 15:51:46 2009: 6178 TonyLawrence
Yes, you can use a numeric increment; see (link)
Tue Nov 2 08:10:52 2010: 9087 Allan
I am guessing you meant
mkdir {A..D}{1..3}{0..9}
instead of
mkdir {A..D}{1..3}{0-9}
for the last example?
Tue Nov 2 10:15:22 2010: 9089 TonyLawrence
Yes, thank you.
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