Less – How to ‘less’ a File Named ‘-‘?

lessstdin

I accidentally created a file with the name - (eg, seq 10 > -). Then I tried to use less to view it, but it just hangs.

I understand that this is happening because less - expects input from stdin, so it does not interpret the - as a file name. I tried less \- but it does not work either.

So, is there any way to indicate less that - is a file and not stdin?

The best I could get is:

find -name '-' -exec less {} +

Best Answer

Just prefix it with ./:

less ./-

Or use redirection:

less < -

Note that since - (as opposed to -x or --foo-- for instance) is considered a special filename rather than an option, the following doesn't work:

less -- -   # THIS DOES NOT WORK

Related Solutions

Cat and Less give different output

The escape sequences ESC [ ... m are called ANSI Escape Sequences. top sends them to your terminal to make it format output in color, bold, inverted text and so on. You never see these characters when running top but you see the resulting format. You could think of it as looking at a webpage in a browser - you don't see the <html>... formatting the content.

When dumping the output of top into a file, you are saving the non-printable escape sequences with everything else. Think of it as saving view source in your browser.

The default for less is to escape terminal control characters, displaying them in a printable form.

The default for cat is to pass them through to your terminal which interprets them and makes it look "normal".

Try less -r /home/user/top_output.txt

   $ man less ...
   -r or --raw-control-chars
          Causes "raw" control characters to be displayed.  
           The default is to display control characters using the caret
           notation; for example, a control-A (octal 001) is displayed as 
           "^A". Warning: when the -r option is used, less cannot keep 
           track of the actual appearance of the screen (since this depends
           on how the screen responds to each type of control
           character).  Thus, various display problems may result, such
           as long lines being split in the wrong place.

Compare to cat -v /home/user/top_output.txt which will escape non-printable characters.

Shell – How to pipe something to less over ssh

You can to pass the command as an argument and use -t to force pseudo terminal allocation.

For example if the seq command needs to run on the remote server:

ssh $REMOTE_HOST -t 'seq 1 100 | less'

If the seq command needs to run on the local machine, so you could use a similar command using inline string <<< (of course the quoting becomes a little difficult):

ssh $REMOTE_HOST -t "less <<< \"$(seq 1 100)\""

Best Answer

Related Solutions

Cat and Less give different output

Shell – How to pipe something to less over ssh

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