とらりもん - Linux training 2 Diff

! File, redirection, pipe:

- Run the following command and check what happens:
$ cal
$ cal > test.txt
$ cat test.txt
$ ls -l test.txt
$ rm test.txt
$ cat test.txt

What are the meaning of ">", "ls -l", "rm"?

- Run the following command and check what happens:
$ date
$ date > test.txt
$ cat test.txt
$ date >> test.txt
$ date > test.txt
$ cat test.txt

What are the meaning of ">>"? How is it different from ">"?

- Run the following command and check what happens:
$ cal
$ cal | head -4
$ cal | tail -4
$ cal | head -5 | tail -2
$ cal | wc
$ cal | head -4 | wc
$ man head
$ man tail
$ man wc

What are the meaning of "|", head, tail, wc?

!Check points
* A symbol ">" means "redirection". It gives outputs not to display but to a file.
* "cat" command displays contents of a file.
* "ls -l" command displays size, date of creation, etc. of a file.
* "rm" command removes (deletes) a file.
* A symbol "|" means "pipe". It gives outputs not to display but to a next command.
* Using pipes, you can connect many commands.