Unix Command Summary
Part Two: More Basic Commands

Printing files

% lp filename

Creating a short file very quickly

% cat > filename type text CTRL-D - everything typed until CTRL-D is stored in filename

Seeing contents of a file on the screen

% cat filename	entire file
% more filename	entire file by pages; RETURN to see one more line, spacebar for a whole page
% less filename	entire file by pages; you can move either direction
% head filename	first 10 lines of the file
% tail filename	last 10 lines of the file
% tail -50 filename	both head and tail can take a number of lines

Copying a file

% cp oldfile dir/newfile	filenames may contain directories also
% cp ofile1 ofile2 ... ofilen subdir	copy the files with same filenames to a different directory

Renaming a file

% mv oldname newname	give the file a new name
% mv ofile1 ofile2 ... ofilen subdir	move the files to a different directory

Giving more than one name to the same file

% ln fname name

if name is a directory, the link is made so an entry of name occurs in the directory name/fname. A link gives another name to the SAME file. Both names will work to get the file; removing one name does not remove the actual file. The file itself will need link (only be removed when all links are deleted).

Changing file protection

% chmod o-w, u+r fname	set fname to be unreadable by others, readable by owner
% chmod a+x	allow everyone to execute the file; if a directory, this permits searching.

Compiling a C program

% cc progname.c	creates executable file a.out. Source file name must end in .c
% cc -o larry progname.c	creates executable file larry

Input/Output Redirection

Redirection works for compiled programs and Unix commands.

% command < inputfile	Take input from file instead of keyboard.
% a.out > outputfile	Write output to file instead of screen.
% a.out < inputfile > outputfile	Read from a file and write to a file.

Communicating with others in the Unix Operating System

% mail	Read and reply to messages.
% mail user1	Send message to user1. A list of users may be given.
% mail user1 < fname	Send the file fname to the user(s) listed.
% write otheruser	Sends message to someone currently logged on. Type the message, ending with CTRL-d.
% talk otheruser	Split-screen messages to and from someone currently logged on.
% mail laurel:csc123456789	Send mail to someone at their Unix account.

Piping the output of one command as the input to another command

% command1 | command2 | command3

Control Characters

CTRL-C	Terminates a process.
CTRL-D	End-of-text character; logout; end a process.
CTRL-Z	Suspends a process (can be restarted).