bash to sh

check.sh

@@ -1,4 +1,4 @@
-#! /usr/bin/env bash
+#! /usr/bin/env sh
 
 set -e
 
@@ -19,11 +19,11 @@ echo "${TARGET}" | grep -q "/" || TARGET="library/${TARGET}"
 
 
 # move tha tag to its own var and remove it from the repo name
-BASE_TAG=$(sed 's/[^:]*://' <<< $BASE)
-TARGET_TAG=$(sed 's/[^:]*://' <<< $TARGET)
+BASE_TAG=$(echo "${BASE}" | sed 's/[^:]*://')
+TARGET_TAG=$(echo "${TARGET}" | sed 's/[^:]*://')
 
-BASE_REPO=$(sed 's/:.*//' <<< $BASE)
-TARGET_REPO=$(sed 's/:.*//' <<< $TARGET) 
+BASE_REPO=$(echo "${BASE}" | sed 's/:.*//')
+TARGET_REPO=$(echo "${TARGET}" | sed 's/:.*//') 
 
 BASE_URL="https://hub.docker.com/v2/repositories/${BASE_REPO}/tags/${BASE_TAG}"
 TARGET_URL="https://hub.docker.com/v2/repositories/${TARGET_REPO}/tags/${TARGET_TAG}"
@@ -31,8 +31,8 @@ TARGET_URL="https://hub.docker.com/v2/repositories/${TARGET_REPO}/tags/${TARGET_
 
 # login if credentias are passed
 HEADER=""
-if [[ ! -z "${DOCKER_USERNAME}" && ! -z "${DOCKER_PASSWORD}" ]]; then
-  TOKEN=$(curl -s -H "Content-Type: application/json" -X POST -d '{"username": "'${DOCKER_USERNAME}'", "password": "'${DOCKER_PASSWORD}'"}' https://hub.docker.com/v2/users/login/ | jq -r .token) 
+if [ -n "${DOCKER_USERNAME}" ] && [ -n "${DOCKER_PASSWORD}" ]; then
+  TOKEN=$(curl -s -H "Content-Type: application/json" -X POST -d '{"username": "'"${DOCKER_USERNAME}"'", "password": "'"${DOCKER_PASSWORD}"'"}' https://hub.docker.com/v2/users/login/ | jq -r .token) 
   HEADER="Authorization: JWT ${TOKEN}"
 fi
 
@@ -44,10 +44,10 @@ TARGET_DATE=$(curl -s -H "${HEADER}" "${TARGET_URL}" | jq -r .last_updated)
 BASE_TIMESTAMP=$(date -d "${BASE_DATE}" +%s)
 TARGET_TIMESTAMP=$(date -d "${TARGET_DATE}" +%s)
 
-if [ $BASE_TIMESTAMP -le $TARGET_TIMESTAMP ]; then
+if [ "$BASE_TIMESTAMP" -le "$TARGET_TIMESTAMP" ]; then
   echo "no update needed"
   exit 1
 fi
 
 echo "$TARGET needs updating"
-exit 0
+exit 0