Read env variable with unescaped characters from file on ubuntu with bash

user_9805867 0
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How to read environmental variable in bash that contains spaces and possibly other characters that need to be escaped?

I have a file server.env

PUBLIC_KEY=ssh-rsa whatever+whatever+8whatever/whatever+p+whatever user@alans-MacBook-Pro.local

I am trying to read this file into bash script as an environmental variable:

export $(cat server.env | xargs)

I am getting an error:

-bash: export: `user@alans-MacBook-Pro.local': not a valid identifier

OK, trying to quote the value in server.env:

PUBLIC_KEY='ssh-rsa whatever+whatever+8whatever/whatever+p+whatever user@alans-MacBook-Pro.local'
  • the same error

Double quote:

PUBLIC_KEY="ssh-rsa whatever+whatever+8whatever/whatever+p+whatever user@alans-MacBook-Pro.local"
  • also errors

What am I missing here?

ubuntu environment-variables bash
3 Answers

Bash provides parameter expansion with substring removal that will allow you to separate the NAME=value pairs read from the server.env file and then export the NAME=value pairs.

A simple read loop is all you need:

#!/bin/bash

while read -r line; do              ## read each line of server.env
    val="${line#*=}"                ## trim to 1st =, save in val
    export ${line%=$val}="$val"     ## remove =$val leaving name, export val with name
done < server.env

printf "%s\n" "$PUBLIC_KEY"         ## confirm

Example Use/Output

$ bash test.sh
ssh-rsa whatever+whatever+8whatever/whatever+p+whatever user@alans-MacBook-Pro.local

Where the basic Parameter Expansions are:

${var#pattern}      Strip shortest match of pattern from front of $var
${var##pattern}     Strip longest match of pattern from front of $var
${var%pattern}      Strip shortest match of pattern from back of $var
${var%%pattern}     Strip longest match of pattern from back of $var

(note: pattern can contain normal shell globs like '*' and '?')

There are literally dozens of useful parameter expansions you can use for string manipulations. Just check man bash under the "Parameter Expansion" heading.

user_34221020

PARTIAL ANSWER (does not export, so the variable is not available in subsequent runs of bash, only in the current session):

source server.env
user_98058670

The problem here is that field splitting still occurs on the whitespace.

You should do this:

export "$(cat server.env)"

(i.e. add double quotes).

For multiple variables, loop over the lines:

while read -r line
do
    export "$line"
done < server.env

If this is in a script called export.sh, then you will also want to source it for the variables to be set in the current process:

source export.sh
user_147225620
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