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Sun Studio 12: Fortran Programming Guide

2.1.4.3 Command-Line I/O Redirection and Piping

Another way to associate a physical file with a program’s logical unit number is by redirecting or piping the preconnected standard I/O files. Redirection or piping occurs on the runtime execution command.

In this way, a program that reads standard input (unit 5) and writes to standard output (unit 6) or standard error (unit 0) can, by redirection (using <, >, >>, >&, |, |&, 2>, 2>&1 on the command line), read or write to any other named file.

This is shown in the following table:

Table 2–1 csh/sh/ksh Redirection and Piping on the Command Line

Action  

Using C Shell  

Using Bourne or Korn Shell  

Standard input— read from mydata 

myprog < mydata

myprog < mydata

Standard output— write (overwrite) myoutput 

myprog > myoutput

myprog > myoutput

Standard output— write/append to myoutput 

myprog >> myoutput

myprog >> myoutput

Redirect standard error to a file 

myprog >& errorfile

myprog 2> errorfile

Pipe standard output to input of another program 

myprog1 | myprog2

myprog1 | myprog2

Pipe standard error and output to another program 

myprog1 |& myprog2

myprog1 2>&1 | myprog2

See the csh, ksh, and sh man pages for details on redirection and piping on the command line.