Re: minor 'cat' enhancement w/ patch (original) (raw)

On 02/11/2013 03:29 PM, Pádraig Brady wrote:

On 02/11/2013 02:56 AM, Tom Warzeka wrote:

Hello! I sometimes use 'cat -E' as a quick check for lines with trailing white space. I understand that '$' was chosen as the end-of-line character due to its usage in regular expressions. However, I like to use a more conspicuous character, such as '@'. So, I thought, how about letting the user specify the end-of-line character? While doable with 'sed', it was quite easy to add an option to accomplish this. My proposed new syntax is:

cat -E -c @ ...

or

cat --show-ends --end-char=@ ...

It is minimally intrusive and does not affect backward compatibility: when one of the new options is not specified, the end-of-line character is still '$'. Alternatively, use of one of these options could automatically turn-on displaying an end-of-line character (just add "show_ends = true;" within the new case).

Here's my patch submitted for your perusal. It is applied to coreutils-8.20, the current latest stable release. If you decide to include it, feel free to make any changes you see fit. Thanks!

-- Tom

Why is @ (or any char) better than $ ? If you wanted to highlight stuff you'd be better with grep or sed:

cat -E < the/file | GREP_COLOR='30;41' grep --color '[[:space:]]*$$'

I don't think there is enough benefit for including this change.

BTW if you're only interested in looking at trailing whitespace, then the trailing $, and thus cat is redundant anyway:

Show all lines with trailing whitespace highlighted

$ GREP_COLOR='41' grep --color '[[:blank:]]*$'

Show lines with trailing whitespace highlighted

$ GREP_COLOR='41' grep --color '[[:blank:]]+$'

cheers, Pádraig.