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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...
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
Last edited by Disillusionist; 05-17-2009 at 01:39 PM.
Reason: Correction
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:
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