How to reuse a variable in shell script when used in curl?

Question

Depending on certain conditions I want to use JWT else I want to provide path to certs. Thus in my shell script this is the code:

if /* some condition */
  authorization='-H "'Authorization': 'Bearer' ${JWT}"'
else
  authorization="--cert "${ADMIN_CERT_PATH}" --key "${ADMIN_KEY_PATH}""

Now the curl request should be: curl -H "Authorization: Bearer 348129" for if condition curl --cert /Users/.../admin_cert --key /Users/../admin_key .. for else path

In order to get that output I need to use the following format in my shell script for if condition

response_code="$(curl -s -o /dev/null -w "%{http_code}" "$authorization" "$status_url")"

and following format for else code:

response_code="$(curl -s -o /dev/null -w "%{http_code}" $authorization "$status_url")"

Note: I need $authorization variable quoted in first case and unquoted in the else case. I do not want to write 2 different curl commands instead reuse the authorization variable. Thus, i need to modify the way I have declared my authorization variable such that I can write any one of the curl commands only once which works for both if and else cases.

Quotes don't nest, and even if they did storing them in variables doesn't work (they're treated as data rather than shell syntax). Use an array instead; see Why does shell ignore quotes in arguments passed to it through variables? P.s. do not use eval. — Gordon Davisson
– Gordon Davisson, Commented Dec 11, 2018 at 5:00

chepner · Accepted Answer · 2018-12-11 12:48:35Z

2

When you are using a shell that supports arrays, you can avoid the need for a temporary configuration file.

curl_opts=(-s -o /dev/null -w "%{http_code}")
if /* some condition */
  curl_opts+=(-H "Authorization: Bearer $JWT")
else
  curl_opts+=(--cert "$ADMIN_CERT_PATH" --key "$ADMIN_KEY_PATH")
fi

...

response_code="$(curl "${curl_opts[@]}" "$status_url")"

answered Dec 11, 2018 at 12:48

chepner

538k77 gold badges594 silver badges746 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

D.Shawley · Accepted Answer · 2018-12-11 12:50:21Z

2

curl supports a way to pass command line parameters in a file that I have used before when I have complex parameters. The idea is to place the complex command-line parameters into a simple text file and instruct curl to read parameters from it using --config parameter.

In this case the shell script would look something like the following.

#!/bin/sh

## "safely" create a temporary configuration file
curlctl=$(mktemp -q -t $(basename "$0"))
if test $? -ne 0
then
    echo "$0: failed to create temporary file, exiting."
    exit 75  # EX_TEMPFAIL
fi
trap 'rm "$curlctl"' 0

## write parameters used in all cases
cat>>"$curlctl" <<EOF
output = /dev/null
silent
write-out = %{http_code}
EOF

## append conditional parameters
if test "$some" = 'condition'
then
    printf 'header = "Authorization: Bearer %s"\n' "$JWT" >> "$curlctl"
else
    echo "cert = $ADMIN_CERT_PATH" >> "$curlctl"
    echo "key = $ADMIN_KEY_PATH" >> "$curlctl"
fi

# uncomment to see what the config file looks like
# cat "$curlctl" | sed 's/^/curl config:   /'

response_code=$(curl --config "$curlctl" http://httpbin.org/get)
echo "response code: $response_code"

The first few lines set up a temporary file that is deleted when the shell script exits. If you are already using trap then your cleanup will probably be more complex.

edited Dec 11, 2018 at 12:50

answered Dec 11, 2018 at 12:40

D.Shawley

59.9k10 gold badges105 silver badges116 bronze badges

2 Comments

chepner Over a year ago

Good answer; I would just avoid using cat when printf 'header = "Authorization: Bearer %s"\n' "$JWT" >> "$curlctl" would work just as well.

D.Shawley Over a year ago

@chepner - I usually fall back to using heredocs to avoid all of the trapfalls and headaches associated with shell quoting but printf would work as well. Then again, the requirement of using hard tabs for <<-EOF is almost as onerous.

Collectives™ on Stack Overflow

How to reuse a variable in shell script when used in curl?

2 Answers 2

Comments

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related