Assign multi-line string to a shell variable or file
# to var
$ sql=$(cat <<EOF
SELECT foo, bar FROM db
WHERE foo='baz'
EOF
)
# file
$ cat <<EOF >> greetings.txt
line 1
line 2
EOF
switch to last directory / between directories
cd -
run last command
!!
(in a bash script) force the script to fail, if any sub-command causes a non-zero exit code
set -e