Show special characters in Unix while using 'less' Command

user_425765 0
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I would like to know how to view special characters while using 'less' command. For instance I want to see the non-printable characters with a special notation. For instance in 'vi' editor I use "set list on" to see the line termination characters represented by dollar '$' character. Similarly I would want to do this using 'less' command.

I referred Unix less manual, but to no avail.

command unix linux
6 Answers

In the same spirit as https://stackoverflow.com/a/6943976/7154924:

cat -A

-A, --show-all
       equivalent to -vET
-v, --show-nonprinting
       use ^ and M- notation, except for LFD and TAB
-E, --show-ends
       display $ at end of each line
-T, --show-tabs
       display TAB characters as ^I

Alternatively, or at the same time, you can pipe to tr to substitute arbitrary characters to the desired ones for display, before piping to a pager like less if desired.

user_71549240

Now, sometimes you already have less open, and you can't use cat on it. For example, you did a | less, and you can't just reopen a file, as that's actually a stream.

If all you need is to identify end of line, one easy way is to search for the last character on the line: /.$. The search will highlight the last character, even if it is a blank, making it easy to identify it.

That will only help with the end of line case. If you need other special characters, you can use the cat -vet solution above with marks and pipe:

  • mark the top of the text you're interested in: ma
  • go to the bottom of the text you're interested in and mark it, as well: mb
  • go back to the mark a: 'a
  • pipe from a to b through cat -vet and view the result in another less command: |bcat -vet | less

This will open another less process, which shows the result of running cat -vet on the text that lies between marks a and b.

If you want the whole thing, instead, do g|$cat -vet | less, to go to the first line and filter all lines through cat.

The advantage of this method over less options is that it does not mess with the output you see on the screen.

One would think that eight years after this question was originally posted, less would have that feature... But I can't even see a feature request for it on https://github.com/gwsw/less/issues

user_82805410
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