Discuss the use of meta-characters in Linux shell, such as redirection and pipe. Provide one example and explain.'
In Linux shell, meta-characters are special characters that have a specific purpose or function. Two commonly used meta-characters are redirection and pipe.
1) Redirection: Redirection is used to redirect the input or output of a command. The most commonly used redirection meta-characters are:
- ">" (greater than): This redirects the standard output of a command to a file, overwriting the file if it already exists.
For example, let's say we have a command that prints some output to the terminal:
$ echo "Hello, World!"
If we want to redirect this output to a file instead of displaying it on the terminal, we can use the ">" meta-character:
$ echo "Hello, World!" > output.txt
This command will create a file named "output.txt" and write the string "Hello, World!" into it. If the file already exists, it will be overwritten.
2) Pipe: The pipe meta-character (|) is used to combine multiple commands by taking the output of one command and using it as the input for another command.
For example, let's say we have two commands:
$ command1
$ command2
If we want to pass the output of command1 as the input to command2, we can use the pipe meta-character:
$ command1 | command2
Here's an example to illustrate its use:
$ ls | grep ".txt"
In this example, "ls" lists all the files in the current directory, and the output is passed through the pipe to "grep". "grep" searches for lines containing the string ".txt" in the input it receives. So, the command will display only the files with the ".txt" extension in the current directory.
Overall, the use of meta-characters in Linux shell, particularly redirection and pipe, provide powerful ways to manipulate input and output streams, enabling more sophisticated and efficient command combinations.