How to pass local variable to remote using ssh and bash script?

Question

``` ssh remotecluster 'bash -s' << EOF > export TEST="sdfsd" > echo $TEST > EOF ``` This prints nothing. Also it still does not work even if I store the variable into file and copy it to remote. ``` TEST="sdfsdf" echo $TEST > temp.par scp temp.par remotecluster ssh remotecluster 'bash -s' << EOF > export test2=`cat temp.par` > echo $test2 > EOF ``` Still prints nothing. So my question is how to pass local variable to the remote machine as a variable ? Answers have been give in this

Accepted Answer

The variable assignment `TEST="sdfsd"` given in the here document is no real variable assignment, i. e. the variable assignment will actually not be performed directly in the declaration / definition of the here document (but later when the here document gets evaluated by a shell).

In addition, the `$TEST` variable contained in an unescaped or unquoted here document will be expanded by the local shell before the local shell executes the `ssh` command. The result is that `$TEST` will get resolved to the empty string if it is not defined in the local shell before the `ssh` command or the here document respectively.

As a result, the variable assignment `export TEST="sdfsd"` in the here document will not take effect in the local shell, but first be sent to the shell of the remote host and only there be expanded, hence your prints nothing experience.

The solution is to use an escaped or single-quoted here document, `<<\EOF` or `<<'EOF'`; or only escape the `\$TEST` variable in the here document; or just define the `$TEST` variable before the `ssh` command (and here document).

```
# prints sdfsd
export TEST="sdfsd"
ssh localhost 'bash -s' << EOF
echo $TEST
EOF

# prints sdfsd
ssh localhost 'bash -s' << EOF
export TEST="sdfsd"
echo \$TEST
EOF

# prints sdfsd
ssh localhost 'bash -s' <<'EOF'
export TEST="sdfsd"
echo $TEST
EOF
```

How to pass local variable to remote using ssh and bash script?

Solution

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