From bbf6566edfa04f188ea6e626f53e5e81b45c3f54 Mon Sep 17 00:00:00 2001
From: Aaron LI <aly@aaronly.me>
Date: Sun, 11 Mar 2018 10:58:29 +0800
Subject: Minor improvements

---
 dfly-update | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/dfly-update b/dfly-update
index ffc87f8..13e4dfe 100755
--- a/dfly-update
+++ b/dfly-update
@@ -93,6 +93,10 @@ debug() {
     [ -n "${DEBUG}" ] && echo "DEBUG: $@" >&2 || true
 }
 
+log() {
+    echo "$@" >&2
+}
+
 warn() {
     echo "WARNING: $@" >&2
 }
@@ -210,7 +214,7 @@ get_latest_image() {
     local url_checksum=$(get_md5list_url ${branch})
     local tmpchecksum=$(mktemp -t ${NAME}) || exit ${EC_TMPFILE}
     local latest_filename latest_md5 line
-    echo "Fetch remote systems checksum: ${url_checksum}" >&2
+    log "Fetch remote systems checksum: ${url_checksum}"
     fetch -q -o ${tmpchecksum} "${url_checksum}" || exit ${EC_FETCH}
     if is_master_branch "${branch}"; then
         line=$(fgrep '.img.bz2' ${tmpchecksum} | tail -n 1)
@@ -228,7 +232,7 @@ get_latest_image() {
 # Extract the version from image filename
 get_version_filename() {
     [ $# -eq 2 ] || \
-        error ${EC_ARGS} "get_version_filename: $@"
+        error ${EC_ARGS} "get_version_filename: invalid arguments: $@"
     local branch="$1"
     local filename="$2"
     local version
@@ -418,7 +422,7 @@ install_system() {
         if [ -f "${file}" ]; then
             file2="${file}.${BAK_SUF}"
             echo -n "   * ${file}  "
-            cp -af "${file}" "${file2}"  # NOTE: do NOT use "mv"
+            cp -pf "${file}" "${file2}"  # NOTE: do NOT use "mv"
             echo "<backed>"
         fi
     done
@@ -592,7 +596,7 @@ Usage:
         Install the new kernel, world, and config files
     cleanup
         Clean up obsolete files, umount and remove image file
-    fly
+    fly | go
         Synthetic command to upgrade the system!
 _EOF_
     echo
-- 
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