here doc

basic here document (stdin redirection)

cat <<MARKER
    $(date) foobar
MARKER

supress parameter and command substitution

cat <<'MARKER'
    $(date) foobar
MARKER

suppress leading tabs

cat <<-MARKER
    $(date) foobar
MARKER

write here document to file

cat >file <<EOT
    $(date) foobar
EOT

assign here document to variable

FOOBAR=$(cat <<EOT
        foobar farboo barfoo boofar 
EOT
)

examples

here document to stderr

cat >&2 <<EOT
usage: script [-h] [-f] /path/to/file
h - help
f - foobar
EOT

ssh session

ssh remote-host <<EOT
echo "local working directory: $PWD"
echo "remote working directory: \$PWD"
uptime
EOT

ex session

ex file <<EOT
:%s/foobar/boofar/g
:wq
EOT

vi session

vi file <<EOT
i
foo
bar
^[
:wq
EOT

ctrl+v esc generates ^[

links

https://tldp.org/LDP/abs/html/here-docs.html

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last updated: Sat Aug 12 14:29:24 2023