Re: annoyances with tr

[Philip Rowlands]

On Tue, 18 Jul 2006, icewind wrote:

> input: "abc123abc"
> call: tr "abc123abc" -d '[^0-9]'
> output:abcabc
>
> regex-rule: "^" is for "negating" the match
>
> output should be "123"

(Please note - the bug-textutils address you mailed suggests that you 
have a rather old version of tr. textutils, fileutils, and sh-utils 
merged a while back into coreutils. Please consider upgrading.)

Firstly, I can't reproduce the example given:
$ tr "abc123abc" -d '[^0-9]'
tr: extra operand `[^0-9]'

The data to be manipulated is not passed to tr on the commandline.

Also, the arguments to tr are not regexs, they're character sets. The 
desired output could be obtained with:

$ echo acb123abc | tr -d -c '0-9'
123

The square brackets are unnecessary in this context, and tr treats them 
as extra characters to be preserved.


Cheers,
Phil