How do I get field from HTTP GET JSON result to file? - json

Question

I am trying to make a HTTP GET request to an API service and push one of the returned fields in the JSON result to a txt file.
Based on this previously asked question: (Getting JSON value from cURL in Linux Bash)
...I have a bash script as follows...
TOKEN_FILE="/myhome/project/resources/auto_token.txt"
AUTH_RESULT=$(curl -i -H "Content-Type: application/json" "https://access.mywebservice.com/access/oauth/token?grant_type=client_credentials&client_id=123456&client_secret=MySecretPassword");
RESULT_FIELDS=$( cat <<EOF | json_reformat | \
sed -rne '/:/s#^\s+"(\w+)":\s+"([^"]+)",?#json_\1="\2"#gp'
[$AUTH_RESULT]
EOF
)
if [ -f "$TOKEN_FILE" ]
then
echo "$RESULT_FIELDS" > "$TOKEN_FILE"
fi
The expected JSON result looks like this (copied from Postman):
{
"access_token": "eyJ5bGciOiJSUzI1NiJ6.eyJzY29wZSI6WyJDUl7iLCJNQVAiLCJQVFkiLCJ8R1QiLCJTVFMiLCJUVEwiXSwiaXNzIjoiaHR0cHM6Ly9hY2Nlc3MtdWF0LWFwaS5jb3JlbG9naWMuYXNpYSIsImVudl9hx2Nlc3NfcmVzdHJpY3QiOmZhbHNlLCJleHAiOjE0NjcyODMwODcsImNsaWVudF9pZCI6IjhhOTY4OGJjIn0.F2iQfVsi9zntOxKYrNRukSIwuQ_LGSi_WMIXKII2A3GOEaqs-WmFTi7az9rvvfDsOl9rHy_s_66A6PiCpPftyw21Fl0aZZRoFcKv2H_zDUHuxOEs8V36jHeLghV7pjHwYI_nG68CIGvfuRWFNzQuiMFWc_i8oB3n5noSd8fQqa4",
"token_type": "bearer",
"expires_in": 43199,
"scope": "PROD1 PROD2 PROD3",
"iss": "https://access.mywebservice.com",
"env_access_restrict": false
}
I get the following errors returned...
bash-4.1$ ./token_renewal_test_05.sh
: command not foundt_05.sh: line 2:
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
115 576 0 576 0 0 2266 0 --:--:-- --:--:-- --:--:-- 30315
: command not foundt_05.sh: line 3:
: command not foundt_05.sh: line 4:
./token_renewal_test_05.sh: line 14: warning: here-document at line 10 delimited by end-of-file (wanted `EOF')
./token_renewal_test_05.sh: line 13: warning: here-document at line 9 delimited by end-of-file (wanted `EOF')
: command not foundt_05.sh: line 13:
lexical error: invalid char in json text.
sed -rne '/:/s#^\s+"(\w+)":\s+"
(right here) ------^
: command not foundt_05.sh: line 10:
./token_renewal_test_05.sh: line 16: syntax error: unexpected end of file
I'm a bit new to bash and despite what appears to be a direct pointer to the issue am having problems resolving this one (note this is version 5)!
Can anyone offer any assistance with this one?
PS: I do not have jq either.
Thanks!
Regards,
Chris

Answer 1

Caveat emptor as per this comment on Parsing JSON with UNIX tools.
A working solution for your format:
eval $(cat <<EOF | \
sed -re 's/(,|\{|\})//g' | \
sed -re 's/"(\w+)":\s*"?([^"]*)"?$/json_\1='\''\2'\''/'
$JSON
EOF
)
set | grep '^json_'
json_access_token=eyJ5bGciOiJSUzI1NiJ6.eyJzY29wZSI6WyJDUl7iLCJNQVAiLCJQVFkiLCJ8R1QiLCJTVFMiLCJUVEwiXSwiaXNzIjoiaHR0cHM6Ly9hY2Nlc3MtdWF0LWFwaS5jb3JlbG9naWMuYXNpYSIsImVudl9hx2Nlc3NfcmVzdHJpY3QiOmZhbHNlLCJleHAiOjE0NjcyODMwODcsImNsaWVudF9pZCI6IjhhOTY4OGJjIn0.F2iQfVsi9zntOxKYrNRukSIwuQ_LGSi_WMIXKII2A3GOEaqs-WmFTi7az9rvvfDsOl9rHy_s_66A6PiCpPftyw21Fl0aZZRoFcKv2H_zDUHuxOEs8V36jHeLghV7pjHwYI_nG68CIGvfuRWFNzQuiMFWc_i8oB3n5noSd8fQqa4
json_env_access_restrict=false
json_expires_in=43199
json_iss=https://access.mywebservice.com
json_scope='PROD1 PROD2 PROD3'
json_token_type=bearer

Answer 2

Thanks again Chepner and Drew
I was having too many issues with Sed (probably due to my lack of exprience). As it turns out, I tried using a lookbehind. Sed doesn't have this but grep does so knowing the strcuture of my JSON response will never chance, I was able to get my token extracted using the following with grep instead...
grep -o -P '(?<="access_token":").*(?=","token_type")'