On Thu, 2 Aug 2012, RW wrote:
On Thu, 02 Aug 2012 13:20:52 +0200
kaltheat wrote:
I tried to replace three letters with three letters by awk using the
sub-routine. I assumed that my regular expression does mean the
following:
match if three letters of any letter of alphabet occurs anywhere in
input
$ echo AbC | awk '{sub(/[[:alpha:]]{3}/,"cBa"); print;}'
AbC
As you can see the result was unexpected.
When I try doing it for at least one letter, it works:
$ echo AbC | awk '{sub(/[[:alpha:]]+/,"cBa"); print;}'
cBa
...
What am I doing wrong?
Or is awk buggy?
Traditional awk implementations don't support {n}, but I think POSIX
implementations should.
Using gawk instead of awk agrees with that. Printing the result of the
sub (the number of substitutions performed) makes it a little more
clear:
% echo AbC | awk '{print sub(/[[:alpha:]]{3}/,"cBa"); print;}'
0
AbC
% echo AbC | gawk '{print sub(/[[:alpha:]]{3}/,"cBa"); print;}'
1
cBa
sed can handle it:
% echo AbC | sed -E 's/[[:alpha:]]{3}/cBa/'
cBa
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