NOAA / NESDIS / National Geophysical Data Center / WDC for SEG, Boulder, Colorado USA

Redirecting Input and Output

Most UNIX programs spit output to the screen and read input from the keyboard. This is known as ``standard input and output'' or ``standard I/O'' in the following. One of the nicest things about UNIX is the ability to redirect input and output. For example, instead of typing input to a program with the keyboard, it can be read from a file using the symbol <. Output can either be put into a file using the symbol >, appended to the end of a file with >> or used as input to another program with the UNIX pipe facility (|).