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quick newb question

I know that >> appends to the bottom of a file...
but what does << do?
I've searched google, and found that google ignores special characters, and there're no entries in the man file or help files, that i could find...

It sends the file on the right of the << as the input for the command.

HTH

Forrest

Quote:

Originally Posted by forrestt (Post 3543821)

It sends the file on the right of the << as the input for the command.

HTH

Forrest

could you elaborate with an example?

There are three standard file handles that you need to know about

stdin 0
stdout 1
stderr 2

Commands take input from stdin, send normal output to stdout and send error messages to stderr

< file sends the contents of file into stdin to be used by command xyz
<< file reads lines of input from the keyboard, until the message "file" is given.

> file or 1> file redirects the normal output to file (replacing the previous content if the file exists)
>> file or 1>> file redirects normal output to file (appending to the end of the file)

2> file redirects the error messages to file (replacing the previous content if the file exists)
2>> file redirects the error messages to file (appending to the end of the file)

2>&1 redirects the error messages to the address for stdout

Quote:

Originally Posted by cynicalpsycho (Post 3543833)

could you elaborate with an example?

Code:

cat << EOF

This is an example of the use of <<



The input is read until you reach a line that just contains EOF.



It could be anything, but typically EOF is used ;)

EOF

The example from Disillusionist is a so-called "here document". If you want to fed a command with a simple string you can use a "here string" using the triple input redirection:

Code:

grep example <<< "A simple example"