post_to_github.sh

#!/bin/sh

GITHUB_PAT_TOKEN=github_pat_xxx
REPO=myuser/myrepo
FILEPATH=online.txt

# echo -n '...' | base64
INCREMENT='Li4u'

FILEINFO=$(curl \
    -X GET \
    -H "Accept: application/vnd.github+json" \
    -H "Authorization: Bearer $GITHUB_PAT_TOKEN" \
"https://api.github.com/repos/$REPO/contents/$FILEPATH" | tr '\n' ' ' | sed 's/\\n//')

SHA=$(echo "$FILEINFO" | sed -E 's/.*"sha": "([^"]*)".*/\1/')
CONTENT=$(echo "$FILEINFO" | sed -E 's/.*"content": "([^"]*)".*/\1/' )

NEWCONTENT="$CONTENT$INCREMENT"

if [ "${#NEWCONTENT}" -gt 32 ]; then
    NEWCONTENT=''
fi

curl \
-X PUT \
-H "Accept: application/vnd.github+json" \
-H "Authorization: Bearer $GITHUB_PAT_TOKEN" \
"https://api.github.com/repos/$REPO/contents/$FILEPATH" \
-d "{\"message\":\"i am online\",\"content\":\"$NEWCONTENT\",\"sha\":\"$SHA\"}"