Merge pull request #3194 from kulla/install-sh-refactoring

Refactoring install.sh

cmd/ipfs/dist/install.sh

 #!/bin/sh
+#
+# Installation script for ipfs. It tries to move $bin in one of the
+# directories stored in $binpaths.
 
 bin=ipfs
+binpaths="/usr/local/bin /usr/bin"
 
-# this script is currently brain dead.
-# it merely tries two locations.
-# in the future maybe use value of $PATH.
+# This variable contains a nonzero length string in case the script fails
+# because of missing write permissions.
+is_write_perm_missing=""
 
-binpath=/usr/local/bin
-if [ -d "$binpath" ]; then
-  mv "$bin" "$binpath/$bin"
-  echo "installed $binpath/$bin"
-  exit 0
-fi
+for binpath in $binpaths; do
+  if mv "$bin" "$binpath/$bin" 2> /dev/null; then
+    echo "Moved $bin to $binpath"
+    exit 0
+  else
+    if [ -d "$binpath" -a ! -w "$binpath" ]; then
+      is_write_perm_missing=1
+    fi
+  fi
+done
+
+echo "We cannot install $bin in one of the directories $binpaths"
 
-binpath=/usr/bin
-if [ -d "$binpath" ]; then
-  mv "$bin" "$binpath/$bin"
-  echo "installed $binpath/$bin"
-  exit 0
+if [ -n "$is_write_perm_missing" ]; then
+  echo "It seems that we do not have the necessary write permissions."
+  echo "Perhaps try running this script as a privileged user:"
+  echo
+  echo "    sudo $0"
+  echo
 fi
+
+exit 1