The here document and the << operator
It is a special type of block of text or code. It is also a special form of I/O redirection. It can be used to feed the command list to an interactive program.
The syntax of the usage of the
here document or the
<< operator is as follows:
command << HERE text1 ….. text 2…. HERE
This tells the shell that the command should receive the data from a current source, such as the
here document, until the pattern is received. In this case, the pattern is
HERE. We have used the delimiter as
HERE. We can use any other word as the delimiter, such as quite or finish. All the text reads up to a pattern; or the
HERE text is used as an input for command. The text or file received by the command is called as the
Here document: ...