Bash Loop with cURL-CodePudding

I am trying to write a bash loop to retrieve a series of numbers using cURL, but I am having trouble understanding how to do it. The code below is an example of how I am trying to retrieve the first million digits of pi, where the API can only accept 1000 digits at a time.

for i in {0..1000000..1000}
    do
    curl 'https://api.pi.delivery/v1/pi?start=$i&numberOfDigits=1000'
    echo $i
    done

Additionally, I would like to write the returned values to a file called pi.txt instead of displaying them in the terminal. Should I use the >>pi.txt command in the terminal or within the script? Can someone help me correct this bash script?

CodePudding user response：

Use double quotes instead of single quotes around your URL in the curl command (single quotes won't allow for the variable expansion you want there)

CodePudding user response：

curl -o pi.txt "https://api.pi.delivery/v1/pi?start=${i}&numberOfDigits=1000"

should work. If not, maybe try removing the square brackets on the variable.

CodePudding user response：

The api returns JSON, so normally you should use jq to get the content.
Something like

for ((i=0; i<1000000; i =1000)); do
  printf "%s" \
    $(curl -s "https://api.pi.delivery/v1/pi?start=$i&numberOfDigits=1000" |
      jq '.content')
done | tr -d '"'

However, in this case you are calling the curl command in a loop, and you should avoid calling additional programs (jq) in a while loop.

for ((i=0; i<1000000; i =1000)); do
  curl -s "https://api.pi.delivery/v1/pi?start=$i&numberOfDigits=1000"
done | tr -cd '[0-9]'

Redirecting to a file in the script or using the commandline are both possible, just what you like best. When you want to see the digits coming through and redirect, use | tee pi.txt at the end.