Input loses string format when running python from bash

Question

I log in through ssh and run bash. In these bash commands, I need to call a specific function in a python file and pass a string argument into this function.

What I have right now:

echo "commands" | ssh into instance

where commands contains

python -c 'from python file import myfunction;
            myfunction({}) ' ... .format(myvariable)

myvariable is a string containing multiple words.

However, when ssh completes and the commands are executed, debugging logs show that the quotes around myvariable are gone and when passed into myfunction, I get an error for undefined input variables.

How do I make sure myvariable stays a string?

Not an answer to your question, but you may want to look into fabric instead of printing commands — loopbackbee
– loopbackbee, Commented Jul 2, 2014 at 19:11

that other guy · Accepted Answer · 2014-07-02 20:36:34Z

This is usually caused by thinking quotes are context aware. They're not.

Example:

var="select * from table where name="value" order by name"

As a human you might think that since this is a SQL statement, obviously bash will know that the quotes in the middle are nested, and will read the string like this:

var="select * from table where name="value" order by name"
                                    |-----| Nested
    |----------------------------------------------------| Everything

Bash, however, isn't that smart. It reads the string like this:

var="select * from table where name="value" order by name"
    |-------------------------------|     |--------------|
           Quoted string #1                   Quoted #2

The literal values are concatenated, with the net effect that the middle quotes "disappear". The statement is equivalent to:

var="select * from table where name=value order by name"

Instead, you have to tell bash that the quotes are literal data with escapes:

var="select * from table where name=\"value\" order by name"

Shellcheck automatically warns about this.

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