less is a terminal pager program on Unix, Windows, and Unix-like systems used to view (but not change) the contents of a text file one screen at a time. It is similar to , but has the extended capability of allowing both forward and backward navigation through the file. Unlike most Unix text editors/viewers, does not need to read the entire file before starting, allowing for immediate viewing regardless of file size. History Mark Nudelman initially wrote less during 1983–85, in the need of a version of more able to do backward scrolling of the displayed text. The name came from the joke of doing "backwards more." Originally, less was developed for Unix, but it has been ported to a number of other operating systems, including MS-DOS, Microsoft Windows, OS/2, and OS-9, as well as Unix-like systems such as Linux. It is still maintained today by Nudelman. To help remember the difference between less and more, a common joke is to say, "," implying that less has greater functionality than . A similar saying is that "less is more, more or less". Usage can be invoked with options to change its behaviour, for example, the number of lines to display on the screen. A few options vary depending on the operating system. While is displaying the file, various commands can be used to navigate through the file. These commands are based on those used by both and . It is also possible to search for character patterns in the file. By default, displays the contents of the file to the standard output (one screen at a time). If the file name argument is omitted, it displays the contents from standard input (usually the output of another command through a pipe). If the output is redirected to anything other than a terminal, for example a pipe to another command, behaves like . The "lesspipe" extension can automatically determine file types such as PDF, multimedia, and compressed archives, and automatically determines which program to launch display the file's information with, such as text from a PDF file, metadata of photos, lists of files in a compressed archive, and content of a single file in a compressed archive. The command-syntax is: less [options] [file_name]... Frequently used options -g: Highlight just the current match of any searched string. -i: Search case-insensitively. -m: Show more detailed prompt, including file position. -N: Show line numbers (useful