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less

opposite of more

References

  • man less

Quickstart

less +F file    # Like `tail -f`
# or
less file       # `less` then press `⇧ + F` = `tail -f`

less -N file    # with line number
# or
less file       # 1.`less` 2.press `-` 3.press `N`

# e.g. use less to view text
grep pattern file | less

Description

more

more : file perusal filter for crt viewing

  • A filter for paging through text one screenful at a time
  • Users should realize that less provides more emulation plus extensive enhancements.
  • Recommend to use less.

Intro

  • Less is a program similar to more, but which allows backward movement in the file as well as forward movement.
  • Also, less does not have to read the entire input file before starting, so with large input files it starts up faster than text editors like vi.

Options

Most options may be changed :

  • either on the command line,
  • or from within less by using the - or -- command

It will take effect after repainting

Percent

Default : -m, --long-prompt with percent into the file

  • -m, --long-prompt Causes less to prompt verbosely (like more), with the percent into the file.
    • By default, less prompts with a colon.
  • -M, --LONG-PROMPT Causes less to prompt even more verbosely than more.

Line Numbers

Default : -n, --line-numbers without line numbers

  • -n, --line-numbers Suppresses line numbers.
    • The default (to use line numbers) may cause less to run more slowly in some cases, especially with a very large input file.
    • Suppressing line numbers with the -n option will avoid this problem.
    • Using line numbers means: the line number will be displayed in the verbose prompt and in the = command, and the v command will pass the current line number to the editor (see also the discussion of LESSEDIT in PROMPTS below).
  • -N, --LINE-NUMBERS Causes a line number to be displayed at the beginning of each line in the display.

Case

Default : -i, --ignore-case case sensitive

  • -i, --ignore-case Causes searches to ignore case; that is, uppercase and lowercase are considered identical.
    • This option is ignored if any uppercase letters appear in the search pattern; in other words, if a pattern contains uppercase letters, then that search does not ignore case.
  • -I, --IGNORE-CASE Like -i, but searches ignore case even if the pattern contains uppercase letters.

Usage

Default

Case sensitive

less <file_path>

Recommended

With percent into the file

less -M <file_path>

With line numbers & percent into the file

less -MN <file_path>

Commands

Interactive Commands

Move

  • j, ^N, … Forward one line
  • k, ^P, … Backward one line
  • f, ^F, w, … Forward one window
  • b, ^B, z, … Backward one window
  • d, ^D Forward one half-window
  • u, ^U Backward one half-window

tail -f

  • F Forward forever; like tail -f !
# Active @ CLI
less +F <file>
# Press interrupt ( Ctrl + C ) to abort

Search

  • /pattern Search forward for (N-th) matching line
  • ?pattern Search backward for (N-th) matching line
  • n Repeat previous search (for N-th occurrence)
  • N Repeat previous search in reverse direction

Jump

  • g, <, … Go to first line
  • G, >, … Go to last line
  • m<letter> Mark the current position with <letter>
  • '<letter> Go to a previously marked position
  • '' Go to the previous position