Occasionally I need to specify a 'path-equivalent' of one of the standard IO streams (stdin, stdout, stderr).Since 99% of the time I work with Linux, I just prepend /dev/ to get /dev/stdin, etc., and this 'seems to do the right thing'. But, for one thing, I've always been uneasy about such a rationale (because, of course, 'it seems to work' until it doesn't). Jan 04, 2003  If you're not going to use them, then by all means redirect them to /dev/null - but if you leave them closed then some data file in your program may end up open on descriptor 2, and some library functions will write to descriptor 2 given sufficient provocation, thus. /is-voiceplay-group-auto-tuned.html. Input/Output Redirection in Unix Most Unix system commands take input (by default) comes from the terminal and the resulting output (stream) is displayed on (or directed to) the monitor.Commands typically get their input from a source referred to as standard input (stdin) and typically display their output to a destination referred to as standard output (stdout) as.

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1. Objectives

Cannot Redirect Standard Input From /dev/null Permission Denied

Learn how to use shell features to make your work faster and easier. All of the features covered in this chapter work with both bash and tcsh.

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Standard Input Redirect From Dev Null Card

This chapter is from the book 

Linux Shell Features

Objectives

After reading this chapter you should be able to:

• List special characters and methods of preventing the shell from interpreting these characters

• Describe a simple command

• Understand command-line syntax and run commands that include options and arguments

• Explain how the shell interprets the command line

• Redirect output of a command to a file, overwriting the file or appending to it

• Redirect input for a command so it comes from a file

• Connect commands using a pipeline

• Run commands in the background

• Use special characters as wildcards to generate filenames

• Explain the difference between a stand-alone utility and a shell builtin

This chapter takes a close look at the shell and explains how to use some of its features. It discusses command-line syntax and describes how the shell processes a command line and initiates execution of a program. This chapter also explains how to redirect input to and output from a command, construct pipelines and filters on the command line, and run a command in the background. The final section covers filename expansion and explains how you can use this feature in your everyday work.

Except as noted, everything in this chapter applies to the Bourne Again (bash) and TC (tcsh) Shells. The exact wording of the shell output differs from shell to shell: What the shell you are using displays might differ slightly from what appears in this book. For shell-specific information, refer to Chapters 8 (bash) and 9 (tcsh). Chapter 10 covers writing and executing bash shell scripts.

How To Use Dev Null

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