Added shellcheck as a github action

.github/workflows/container_build.yml

@@ -4,10 +4,15 @@ on: [ push,workflow_dispatch ]
 jobs:
   build:
     name: Build and push image
+    environment: MainCI
     runs-on: ubuntu-20.04
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
+
+    - name: Shellcheck
+      id: Shellcheck
+      uses: ludeeus/action-shellcheck@master
 
     - name: Build Image
       id: build-image

run-vsftpd.sh

@@ -7,7 +7,8 @@ fi
 
 # If no env var has been specified, generate a random password for FTP_USER:
 if [ "$FTP_PASS" = "**Random**" ]; then
-    export FTP_PASS=`cat /dev/urandom | tr -dc A-Z-a-z-0-9 | head -c${1:-16}`
+	FTP_PASS=$(tr -dc A-Z-a-z-0-9 </dev/urandom | head -c"${1:-16}")
+	export FTP_PASS
 fi
 
 # Do not log to STDOUT by default:
@@ -26,24 +27,15 @@ echo -e "${FTP_USER}\n${FTP_PASS}" > /etc/vsftpd/virtual_users.txt
 
 # Set passive mode parameters:
 if [ "$PASV_ADDRESS" = "**IPv4**" ]; then
-    export PASV_ADDRESS=$(/sbin/ip route|awk '/default/ { print $3 }')
+    PASV_ADDRESS=$(/sbin/ip route|awk '/default/ { print $3 }')
+    export PASV_ADDRESS
 fi
 
-echo "pasv_address=${PASV_ADDRESS}" >> /etc/vsftpd/vsftpd.conf
-echo "pasv_max_port=${PASV_MAX_PORT}" >> /etc/vsftpd/vsftpd.conf
-echo "pasv_min_port=${PASV_MIN_PORT}" >> /etc/vsftpd/vsftpd.conf
-echo "pasv_addr_resolve=${PASV_ADDR_RESOLVE}" >> /etc/vsftpd/vsftpd.conf
-echo "pasv_enable=${PASV_ENABLE}" >> /etc/vsftpd/vsftpd.conf
-echo "file_open_mode=${FILE_OPEN_MODE}" >> /etc/vsftpd/vsftpd.conf
-echo "local_umask=${LOCAL_UMASK}" >> /etc/vsftpd/vsftpd.conf
-echo "xferlog_std_format=${XFERLOG_STD_FORMAT}" >> /etc/vsftpd/vsftpd.conf
-echo "reverse_lookup_enable=${REVERSE_LOOKUP_ENABLE}" >> /etc/vsftpd/vsftpd.conf
-echo "pasv_promiscuous=${PASV_PROMISCUOUS}" >> /etc/vsftpd/vsftpd.conf
-echo "port_promiscuous=${PORT_PROMISCUOUS}" >> /etc/vsftpd/vsftpd.conf
-echo "listen_port=${LISTEN_PORT}" >> /etc/vsftpd/vsftpd.conf
+{ echo "pasv_address=${PASV_ADDRESS}"; echo "pasv_max_port=${PASV_MAX_PORT}"; echo "pasv_min_port=${PASV_MIN_PORT}"; echo "pasv_addr_resolve=${PASV_ADDR_RESOLVE}"; echo "pasv_enable=${PASV_ENABLE}"; echo "file_open_mode=${FILE_OPEN_MODE}"; echo "local_umask=${LOCAL_UMASK}"; echo "xferlog_std_format=${XFERLOG_STD_FORMAT}"; echo "reverse_lookup_enable=${REVERSE_LOOKUP_ENABLE}"; echo "pasv_promiscuous=${PASV_PROMISCUOUS}"; echo "port_promiscuous=${PORT_PROMISCUOUS}"; echo "listen_port=${LISTEN_PORT}"; } >> /etc/vsftpd/vsftpd.conf
 
 # Get log file path
-export LOG_FILE=`grep xferlog_file /etc/vsftpd/vsftpd.conf|cut -d= -f2`
+LOG_FILE=$(grep xferlog_file /etc/vsftpd/vsftpd.conf|cut -d= -f2)
+export LOG_FILE
 
 # stdout server info:
 if [ ! $LOG_STDOUT ]; then
@@ -63,7 +55,7 @@ cat << EOB
 	· Redirect vsftpd log to STDOUT: No.
 EOB
 else
-    /usr/bin/ln -sf /dev/stdout $LOG_FILE
+    /usr/bin/ln -sf /dev/stdout "$LOG_FILE"
 fi
 
 # Run vsftpd: