# Basics of Linux ### Streams

# Standard streams
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- Standard input
                          - `#0`
                          - `stdin`
                        - Standard output
                          - `#1`
                          - `stdout`
                        - Standard error
                          - `#2`
                          - `stderr`

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- Usually resolve to the user's current terminal

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                        ---
                        # Output
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> "Redirect standard output (stdout) into a file, overwrite."

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```txt
                        $ command > out-file

```

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                        ---
                        # Errors
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> "Redirect standard error (stderr) into a file, overwrite."

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```txt
                        $ command 2> err-out-file

```

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                        ---
                        # Output and errors
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> "Redirect both, standard output (stdout) and standard error (stderr), into a file. Overwrite."

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```txt
                        $ command &> out-n-err-file

```

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                        ---
                        # Input
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> "Get the standard input (stdin) from a file.""

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```txt
                        $ command < in-file

```

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                        ---
                        # Append and multiple redirections
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> "Redirect both, append standard output (stdout) and standard error (stderr) into separate files."

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```txt
                        $ command >> append-out-file 2>> append-err-file

```

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                        ---
                        # Piping
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                                <img src="/img/sld-linux-1-streams-01.svg" style="width: 300px;transform: translateY(480px);" alt="A similar pipe that 8-bit Mario games had.">
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                        ---
                        # Piping output
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> "The standard output (stdout) of command1 will be the standard input (stdin) for command2."

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```txt
                        $ command1 | command2

```

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                        ---
                        # Piping output and errors
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> "Both standard output (stdout) and error (stderr) of command1 will be the standard input (stdin) for command2."

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```txt
                        $ command1 2>&1 | command2

```
                        - bash supported version:

```txt
                        $ command1 |& command2

```

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Thank you

Joona Tolonen

servicedesk@csc.fi