Echo (computing)

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echo means several things in computing.

Contents 1 Terminal command 2 Ping 3 Server 4 References

[edit] Terminal command

echo is a command in Unix (and by extension, its descendants, such as Linux) and MS-DOS that places a string on the terminal. It is typically used in shell scripts and batch programs to output status text to the screen or a file.

$ echo This is a test.
This is a test.
$ echo "This is a test." > ./test.txt
$ cat ./test.txt
This is a test.

Some variants of Unix support options such as -n and -e. These are not standard^[1] due to historical incompatibilities between BSD and System V; the printf command can be used in situations where this is a problem.

[edit] Ping

echo refers to a ping request. See RFC 792.

[edit] Server

An echo server is a standard service implementing the ECHO protocol that runs on TCP port 7. Intended for testing purposes, it replies to all packets with a packet containing the same data. It is rarely used in practice.

[edit] References

1. ^ IEEE Std 1003.1, 2004, documentation for echo

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