CertiGuide to A+ (A+ 4 Real)  9  Chapter 5: The Linux Operating System       9  Basic Concepts and Procedures for Creating, Viewing and Editing Files and Directories            9  Common Commands

cat - Concatenate Files And Print To The Standard Output 1 head, tail - Output the First or Last Part of a File to the Screen

There are two command line file viewers in Linux called more and less. More was the original file viewer written for UNIX, which had limited ability to move forwards and backwards through a file. Less, its younger brother was written to be an enhancement to more expanding the feature set and giving it additional functionality. Although many enhancements have been written for both utilities, even today less still has more capability then more. They can be invoked by:

more [options] file_name

less [options] file_name

This displays the beginning of the file on the screen. The next table lists a basic set of commands for more and less. Notice that more does not support use of the arrow keys to move forward to a backward in a file where as less supports this additional functionality. The f key will move forward through the file one page at a time, the return or enter key will move forward one line at a time and the enter key will move forward through the file one line at a time. The b key will move backwards through the file one page at a time.

Table 12 provides a summary of the keys used by more/less and what they do.

Table 12: more/less Keys Commands

Function Group	Key	Command
General	h, H	Display help.
	q, Q, ZZ	Exit.
Moving	DownArrow, j, CR	Forward one line (or N lines).
	UpArrow, k	Backward one line (or N lines).
	f, ^F, SPACE	Forward one window (or N lines).
	b, ^B	Backward one window (or N lines).
	z	Forward one window (and set window to N).
	w	Backward one window (and set window to N).
	ESC-(, RightArrow	Left 8 character positions (or N positions).
	ESC-), LeftArrow	Right 8 character positions (or N positions).
Searching	/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.
Jumping	g, < , ESC-<	Go to first line in file (or line N).
	G, > , ESC->	Go to last line in file (or line N).
	p, %	Go to beginning of file (or N percent into file).
	v	Edit the current file with vi
	V	Print version number of "less".

cat - Concatenate Files And Print To The Standard Output 1 head, tail - Output the First or Last Part of a File to the Screen

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