cat file with no line wrap

Question

In *nix, how do I display (cat) a file with no line-wrapping? Longer lines should be cut such that they fit into the screen width.

Answer 1

You may be looking for fmt:

fmt file

This pretty aggressively reformats your text, so it may do more than what you want.

Alternatively, the cut command can cut text to a specific column width, discarding text beyond the right margin:

cat file | cut -c1-80

Another handy option is the less -S command, which displays a file in a full screen window with left/right scrolling for long lines:

less -S file

• Alexandru: Indeed, it does more than I want: it concatenates lines.
• Alexandru: Actually, I'm watching the content of the file using watch "cat file" so I can't use less. cat file | cut -c1-80 did the trick, partially. Any way to adjust the cut to the screen size?
• mob: You may have the environment variable $COLUMNS defined: try cut -c1-$COLUMNS file
• SO Stinks: Cool. The "less -S" version is pretty awesome.
• Jo So: You can toggle wrapping while less is running using the key combination -S

Answer 2

Note that cut accepts a filename as an argument.

This seems to work for me:

watch 'bash -c "cut -c -$COLUMNS file"'

For testing, I added a right margin:

watch 'bash -c "cut -c -$(($COLUMNS-10)) file"'

When I resized my terminal, the truncation was updated to match.

• Dennis Williamson: When I run your script watch ./colscript, I see 80 displayed. When I change the width by dragging the edge of the window (I'm using PuTTY) the number changes to match. What do you see?
• Alexandru: I see nothing, but I figured out why: different bash versions. watch ./colscript works on bash 4.0 (my computer), but not on bash 3.0 (a remote computer). ./colscript doesn't work on any of the two versions.
• Dennis Williamson: echo $BASH_VERSION gives me "3.2.48(1)-release" The reason that running ./colscript from the command line echoes a blank line is that $COLUMNS is only populated for interactive shells. You can try added -i at the end of the first line of ./colscript so you have #!/bin/bash -i

Answer 3

as stated by others, the answer is cut -c ..., but to add some dynamic to it, I prefer this:

cat file.txt |cut -c -$(tput cols)

• Aquarius Power: this limits the output to a specified (but dynamic) columns length

Answer 4

to toggle long-line-wrap in less. Default is to wrap.

- `less file`
- in file type `"-S"` to toggle to truncate on line width
- to toggle back `"-S"` again.

• Dennis Williamson: You can also call less with -S as an option: less -S file or include it in your environment: export LESS="-S" (plus other options). In either case, you can still use the toggle once it's running if you want.

Answer 5

The use of cut does not take into account that tabs are considered a single character \t but they are printed as 8 blank spaces. Thus a file with tabs will be cut at different perceived columns.

less -S truncates optimally the text, also in the presence of tabs, but AFAIK it cannot be used to non-interactively print the "chopped" file.

A working solution is to convert tabs into spaces through expand and then cut the output: expand < file | cut -c -$(tput cols)

• Lambart: expand is a great help; thanks, I was just wrestling with this issue (with tabs). Glad I scrolled to the bottom!

Answer 6

Other solution, this time using paginate command pr

echo "your long line" | pr -m -t -w 80