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Standard input and standard output

From: Unix for Mac OS X Users

Video: Standard input and standard output

In this chapter we're going to be talking about how we can modify the input and output that Unix uses and before we use do that we first need to understand the concept of standard input and standard output and you may already be able to guess what these standard input and output are if you think about it. The input is the keyboard. That's its main way of getting input into Unix. It's the things that you type on the keyboard and the way of getting information out, standard output, is typically the text Terminal, the window, the screen that you're seeing inside Terminal. So that's where it outputs its results to. So when we type a command, we type in the command, we hit Return, that's the input.

Standard input and standard output

In this chapter we're going to be talking about how we can modify the input and output that Unix uses and before we use do that we first need to understand the concept of standard input and standard output and you may already be able to guess what these standard input and output are if you think about it. The input is the keyboard. That's its main way of getting input into Unix. It's the things that you type on the keyboard and the way of getting information out, standard output, is typically the text Terminal, the window, the screen that you're seeing inside Terminal. So that's where it outputs its results to. So when we type a command, we type in the command, we hit Return, that's the input.

It does its process and at the end of it, it outputs the results to the screen so that we can see it. What we're going to be doing is changing each of those. I also want to mention the common abbreviations for standard input are just stdin and for output its stdout. So if you see that, that's what it is referring to, is standard in and standard out, and there are actually sort of special files on Unix that correspond to these and that's inside that dev folder. dev is where information about different devices stored. So inside dev there is a stdin and stdout, which are files that are really sort of references to these two things, to the keyboard and to the Terminal.

What we want to do is figure out how we can work with commands so that we can change the input or the output. So let's start by looking in the next movie at how we can direct the output not to the screen, but instead to go into a file.

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This video is part of

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Unix for Mac OS X Users

82 video lessons · 25420 viewers

Kevin Skoglund
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  1. 3m 57s
    1. Introduction
      1m 14s
    2. Using the exercise files
      2m 43s
  2. 32m 2s
    1. What is Unix?
      7m 27s
    2. The terminal application
      4m 23s
    3. Logging in and using the command prompt
      5m 19s
    4. Command structure
      5m 22s
    5. Kernel and shells
      5m 25s
    6. Unix manual pages
      4m 6s
  3. 15m 58s
    1. The working directory
      2m 49s
    2. Listing files and directories
      3m 59s
    3. Moving around the filesystem
      4m 58s
    4. Filesystem organization
      4m 12s
  4. 1h 4m
    1. Naming files
      5m 41s
    2. Creating files
      2m 19s
    3. Unix text editors
      6m 39s
    4. Reading files
      5m 35s
    5. Reading portions of files
      3m 27s
    6. Creating directories
      2m 40s
    7. Moving and renaming files and directories
      8m 32s
    8. Copying files and directories
      3m 7s
    9. Deleting files and directories
      3m 38s
    10. Finder aliases in Unix
      4m 10s
    11. Hard links
      5m 30s
    12. Symbolic links
      6m 36s
    13. Searching for files and directories
      6m 32s
  5. 34m 58s
    1. Who am I?
      4m 3s
    2. Unix groups
      1m 52s
    3. File and directory ownership
      6m 41s
    4. File and directory permissions
      4m 27s
    5. Setting permissions using alpha notation
      6m 49s
    6. Setting permissions using octal notation
      3m 49s
    7. The root user
      1m 57s
    8. sudo and sudoers
      5m 20s
  6. 52m 34s
    1. Command basics
      4m 4s
    2. The PATH variable
      4m 13s
    3. System information commands
      3m 40s
    4. Disk information commands
      6m 8s
    5. Viewing processes
      5m 0s
    6. Monitoring processes
      3m 36s
    7. Stopping processes
      3m 19s
    8. Text file helpers
      6m 50s
    9. Utility programs
      7m 28s
    10. Using the command history
      8m 16s
  7. 20m 39s
    1. Standard input and standard output
      1m 24s
    2. Directing output to a file
      4m 13s
    3. Appending to a file
      2m 44s
    4. Directing input from a file
      5m 28s
    5. Piping output to input
      4m 40s
    6. Suppressing output
      2m 10s
  8. 41m 28s
    1. Profile, login, and resource files
      9m 11s
    2. Setting command aliases
      6m 59s
    3. Setting and exporting environment variables
      4m 54s
    4. Setting the PATH variable
      6m 10s
    5. Configuring history with variables
      6m 17s
    6. Customizing the command prompt
      6m 5s
    7. Logout file
      1m 52s
  9. 1h 25m
    1. grep: Searching for matching expressions
      5m 21s
    2. grep: Multiple files, other input
      4m 28s
    3. grep: Coloring matched text
      2m 57s
    4. Introduction to regular expressions
      3m 22s
    5. Regular expressions: Basic syntax
      3m 19s
    6. Using regular expressions with grep
      5m 20s
    7. tr: Translating characters
      8m 17s
    8. tr: Deleting and squeezing characters
      5m 30s
    9. sed: Stream editor
      7m 45s
    10. sed: Regular expressions and back-references
      7m 8s
    11. cut: Cutting select text portions
      7m 42s
    12. diff: Comparing files
      4m 35s
    13. diff: Alternative formats
      4m 30s
    14. xargs: Passing argument lists to commands
      7m 25s
    15. xargs: Usage examples
      7m 59s
  10. 42m 25s
    1. Finder integration
      4m 45s
    2. Clipboard integration
      5m 5s
    3. Screen capture
      3m 42s
    4. Shut down, reboot, and sleep
      3m 34s
    5. Text to speech
      2m 36s
    6. Spotlight integration: Searching metadata
      3m 41s
    7. Spotlight integration: Metadata attributes
      4m 24s
    8. Using AppleScript
      5m 23s
    9. System configurations: Viewing and setting
      5m 51s
    10. System configurations: Examples
      3m 24s
  11. 1m 26s
    1. Conclusion
      1m 26s

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