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2.7 KiB
2.7 KiB
Linux metacharacters
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;
: Separates commands.command1 ; command2 # Run command1, then run command2 regardless of whether command1 succeeded.
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&
: Background execution.command & # Runs "command" in the background.
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&&
: AND operator.command1 && command2 # Run command1, then run command2 only if command1 succeeded.
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||
: OR operator.command1 || command2 # Run command1, then run command2 only if command1 failed.
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|
: Pipe operator.command1 | command2 # Output of command1 is passed as input to command2.
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()
: Command group.(command1; command2) # Group commands into a subshell.
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{}
: Command block.{ command1; command2; } # Group commands in the current shell.
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$()
: Command substitution.echo $(command) # Runs "command" and substitutes its output in place.
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``
(Backticks): Another way of command substitution.echo `command` # Same as above, but this syntax can be harder to spot.
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>
: Output redirection.command > file # Redirect the output of command to a file, overwriting the file.
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>>
: Append output.command >> file # Append the output of command to a file.
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<
: Input redirection.command < file # Use "file" as input for command.
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2>
: Error redirection.command 2> file # Redirect the error output of command to a file, overwriting the file.
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2>>
: Append error output.command 2>> file # Append the error output of command to a file.
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&>
: Redirect all output (stdout and stderr).command &> file # Redirect all output of command to a file, overwriting the file.
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*
: Wildcard.ls *.txt # List all .txt files.
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?
: Single character wildcard.ls ?.txt # List all .txt files with a single character name.
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[]
: Character class.ls [ab]*.txt # List all .txt files starting with 'a' or 'b'.
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!
: Negation.command1; ! command1 # Execute command1, then execute command1 again only if the first execution failed.
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#
: Comment.# This is a comment in Bash.
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\$
: Escape character.echo \$HOME # prints $HOME, not the value of the variable.
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\"
: Escape character for quotes.echo "This is a \"quote\"" # prints This is a "quote".
Be careful, especially when using redirections, as they can overwrite your files without warning if you're not careful.