Here Document

Here Document

Syntax:

command << label
input line 1
…
input line n
label

This allows you to redirect input to a shell script from within the shell script itself.

• << label indicates that label marks the end of the here document
• label must appear on a line by itself to end the here document
• << 'label' prevents the shell from doing parameter and command substitution in the here document
• <<- label deletes leading tabs (but not spaces) from the here document

Here Document Example
(from page 189 in "Learning the Korn Shell")

pgmname=$1
for user in $(ypcat passwd | cut -f1 -d:)
do
mail $user <<- EOF
Dear user,
A new version of $pgmname has been installed
in $(whence $pgmname).
Regards,
Your friendly sysadmin
EOF
done

原文：http://snap.nlc.dcccd.edu/reference/scarlatos/cis2.50/note6.html