Joseph Hallenbeck
January 12, 2018

Shell Notes: Less

Filed under: Software Development part of Notes

One of my professional goals this year is to make a marked improvement on my shell (zsh) and editor (vim) skills. I know enough commands to get me through the work day, yet every time I see a real shell or vim poweruser go to town, I am reminded that I am probably only confident in 10% of the commands that I could be using.

Every now and then, I’ll force myself to use h, j, k, l instead of ←, ↑, ↓, → to navigate in Vim and my Tmux panels. The skill lasts about a week before I’m back to the arrow keys and mouse. Every now and then, I’ll try to expand beyond ls, grep, cd, cp, mkdir, mv, rm, pwd, clear and cat, in the shell. I always rebound after a couple weeks, because I can get 90% done with those nine programs.

Hence, a series of articles summarizing the man pages for different applications. A process that hopefully sees me making more regular use of them.


My typical solution to navigating a read-only text file is clear && cat $filename and then scrollback with the mouse or to pipe. My solution to log files are to pipe them into text files and open them in Vim (not recommended on memory-limited systems). So my first Unix command for the year is less, that wonderful program that I get dumped into by Git all the time.

Less is a program that outputs a text file or stream with a buffer to display either more of the stream or page up to previously output lines.

Less gives me something that I’ve been trying, incorrectly to do with clear && cat all along: display a buffer of just the text file. With my old solution, on long file outputs, it was easy to scroll up past the start of the file and into old commands. With Less, this isn’t a problem. The buffer starts and ends with the contents of the text file. Likewise, I frequently output formatted excerpts from my Todo List using the XP and LSGP/LSGC add-ons and pipe them into text files or open new terminals to have a clean buffer to scroll back on. Less solves this by outputing the multi-screen-height output into a single buffer.

Useful Commands/Options

SPACE Scroll down a screen.
RETURN Scroll down one line.
d Scroll down half a page.
u Scroll up half a page
y Scroll up one line.
F Scroll to the end then tail the stream.
g Go to line N
G Go to end of file.
m + Char Marks position with that letter.
’ + Char Return to marked position.
/ Search forward
? Search backwards
@ Search for pattern in file
n Repeat search to next result
N Repeat serach to previous result
t Go to next tag
T Go to previous tag
v Open file in Vim
! + Cmd Invokes shell from inside less
-R Terminal colors maintained
-N Show line numbers
-JM Status columns
"Shell Notes: Less" by Joseph Hallenbeck is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.