Assign a value to a variable inside a loop

Question

I have this code :

HOSTS="host1 host2"
    For hostname in ${HOSTS} ;
do ssh -tt ${USERNAME}@${hostname} << EOF
HOSTSN="test"
echo ${HOSTSN}
exit
EOF
Done

The variable HOSTSN is empty, can you tell me why?

guntbert · Accepted Answer · 2016-12-17 18:09:56Z

1

HOSTSN is empty because it is being evaluated at the time of the

do ssh -tt ${USERNAME}@${hostname} << EOF

execution. Using echo \${HOSTSN} instead will fix it.

Consider this example. Here a file 'foo' is created. The contents are not executed at the time of file creation. So $NAME is not set to anything.

$ cat >foo <<EOF
NAME=Steve
echo Hello ${NAME}
EOF
$

$ cat foo
Hello
$

By introducing a \ character, the variable is not evaluated at the time of file creation.

$ cat >foo <<EOF
NAME=Steve
echo Hello \${NAME}
EOF
$

$ cat foo
Hello Steve
$

guntbert

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answered Oct 27, 2016 at 9:34

steve

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