How to set multiple environment variables from output of other command in bash?

Question

I set a variable that contains multiple values. (this is what I get from heroku config --shell, redacted)
The command to save command output was

envvars=`heroku config --shell -a heroku-app`

And echo "$envvars" result is like this:

BH_SERVER=000000000000000000
DATABASE_URL='postgres://stringno1:[email protected]:5432/randomstring2'
DISCORD_TOKEN=some.veryveryveryvery.long.token.string
EXM_SERVER=000000000000000001
MUTED_SERVER='000000000000000002, 000000000000000003'
SUPER_USER='000000000000000004, 000000000000000005'
TEST_SERVER=000000000000000006
TZ=Asia/Seoul

Now I want to set these values to environment variables. These must not be permanant because these are only needed by python app which will be executed later in script. I think I can use = as delimiter for distinguish key and value but not 100% sure about that. (I don't know how heroku convar works well)

I expect these-like output.

echo $BH_SERVER
# 000000000000000000
echo $DATABASE_URL
# postgres://stringno1:[email protected]:5432/randomstring2
# Note that there is no ' in start and end of line
echo $DISCORD_TOKEN
# some.veryveryveryvery.long.token.string
# Note that . is still there.
echo $MUTED_SERVER
# 000000000000000002, 000000000000000003
# Even if there is space in string, it should be treated as one line
# Also, there is no ' in start and end of line
echo $TZ
# Asia/Seoul
# / is not interpreted. I think this is normal.

There are some already-answered question but I don't find any answer that match my condition.

I put git-bash tag because I am working on Git Bash but I think solution of this question would be same as Bash.

@Lety you mean eval $envvar? that just stops script working. I think it is waiting user input but not sure. — tetratheta
– tetratheta, Commented Dec 9, 2020 at 11:41

John Kugelman · Accepted Answer · 2020-12-09 13:03:28Z

2

You can use eval. Make sure to use the double quotes or else the settings with spaces and quotes will get mangled.

eval "$envvars"

or

eval "$(heroku config --shell -a heroku-app)"

You can use a subshell to isolate the changes to a section of code.

# Parentheses create a subshell, or child process.
# Variables set in a child process don't affect the parent.
(
    eval "$(heroku config --shell -a heroku-app)"
    echo "$BH_SERVER"
    echo "$DATABASE_URL"
    echo "$DISCORD_TOKEN"
    echo "$MUTED_SERVER"
    echo "$TZ"
)

# The variables will be unset here.

edited Dec 9, 2020 at 13:03

answered Dec 9, 2020 at 12:57

John Kugelman

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Comments

Mani · Accepted Answer · 2020-12-09 12:44:36Z

1

You can add echo output to temporary file, source the file and then delete the temp file :

echo $envvars > /tmp/tmp.env && source /tmp/tmp.env && rm /tmp/tmp.env

If on gitbash /tmp is not available, use another available path to create the temporary file

Alternately you can use below format which will not need temporary file

echo $envvars | source /dev/stdin

edited Dec 9, 2020 at 12:44

answered Dec 9, 2020 at 12:21

Mani

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4 Comments

tetratheta Over a year ago

surprisingly, it works! I don't like concept of 'creating new temporary file' but it works. I wonder is there any way to not create 'temporary' files though... Thanks anyway.

Mani Over a year ago

I have modified the answer, Can you try the second format without the temp file "echo $envvars | source /dev/stdin"

John Kugelman Over a year ago

The second one won't work. Pipelines run in subshells.

tetratheta Over a year ago

second method doesn't work. git-bash seems don't like /dev/stdin stuff. Anyway, it seems git-bash seems using Windows' own temporary directory(%temp%) which is nice to know.

Konstantin · Accepted Answer · 2020-12-09 13:07:10Z

0

I'm not sure but this should work

eval $(echo $envvars) ./script.sh

or

eval $(echo $envvars) python script.py

edited Dec 9, 2020 at 13:07

answered Dec 9, 2020 at 12:16

Konstantin

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2 Comments

tetratheta Over a year ago

both doesn't work neither. it says 'not a valid identifier' when processing '0000, 0000'-like lines

Konstantin Over a year ago

I've updated the anwer to address this case

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