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Bash 3.00 brace expansion

© October 2005 Tony Lawrence

Ah, finally: no more of

for i in 1 2 3 4 5 6 7 8 9 0
.. whatever

With Bash 3.0, we now have brace expansion for lists:

for i in {1..10}  
 echo $i 

And, happily:

for i in {10..1}  
 echo $i 

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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-> Bash 3.00 brace expansion


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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.

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


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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