don't send --auth option if TRANSMISSION_USER/PASS are unset

Handle the common case of localhost-only transmission running without authentication

Author: dlenski

manual-tracker-add.sh

@@ -1,6 +1,10 @@
 #!/bin/bash
-# Get transmission credentials
-auth=${TRANSMISSION_USER:-user}:${TRANSMISSION_PASS:-password}
+# Get transmission credentials, if set
+if [[ -n "$TRANSMISSION_USER" && -n "$TRANSMISSION_PASS" ]]; then
+    auth="${TRANSMISSION_USER:-user}:${TRANSMISSION_PASS:-password}"
+else
+    auth=
+fi
 host=${TRANSMISSION_HOST:-localhost}
 list_url=${TRACKER_URL:-https://raw.githubusercontent.com/ngosang/trackerslist/master/trackers_all.txt}
 
@@ -15,7 +19,7 @@ add_trackers () {
 for tracker in $(curl --location -# "${base_url}") ; do
     echo -en "\e[0m"
     echo -ne "\e[93m*\e[0m ${tracker}..."
-if transmission-remote "$host" --auth="$auth" --torrent "${torrent_hash}" -td "${tracker}" | grep -q 'success'; then
+if transmission-remote "$host" ${auth:+--auth="$auth"} --torrent "${torrent_hash}" -td "${tracker}" | grep -q 'success'; then
     echo -e '\e[91m failed.'
     echo -en "\e[0m"
 else
@@ -27,10 +31,10 @@ done
 }
 
 # Get list of active torrents
-ids=${1:-"$(transmission-remote "$host" --auth="$auth" --list | grep -vE 'Seeding|Stopped|Finished' | grep '^ ' | awk '{ print $1 }')"}
+ids=${1:-"$(transmission-remote "$host" ${auth:+--auth="$auth"} --list | grep -vE 'Seeding|Stopped|Finished' | grep '^ ' | awk '{ print $1 }')"}
 
 for id in $ids ; do
-    hash="$(transmission-remote "$host" --auth="$auth"  --torrent "$id" --info | grep '^  Hash: ' | awk '{ print $2 }')"
-    torrent_name="$(transmission-remote "$host" --auth="$auth"  --torrent "$id" --info | grep '^  Name: ' |cut -c 9-)"
+    hash="$(transmission-remote "$host" ${auth:+--auth="$auth"}  --torrent "$id" --info | grep '^  Hash: ' | awk '{ print $2 }')"
+    torrent_name="$(transmission-remote "$host" ${auth:+--auth="$auth"}  --torrent "$id" --info | grep '^  Name: ' |cut -c 9-)"
     add_trackers "$hash"
 done