Fix sudo error in docker systems

Author: LimHyungTae

scripts/install_latest_cmake.bash

@@ -1,7 +1,21 @@
 #!/usr/bin/env bash
 set -e
 
-SUDO=${SUDO:=sudo} # SUDO=command in docker (running as root, sudo not available)
+command_exists() {
+  command -v "$@" >/dev/null 2>&1
+}
+
+user_can_sudo() {
+  command_exists sudo || return 1
+  ! LANG= sudo -n -v 2>&1 | grep -q "may not run sudo"
+}
+
+if user_can_sudo; then
+SUDO="sudo"
+else
+SUDO="" # To support docker environment
+fi
+
 if [ "$1" == "assume-yes" ]; then
     APT_CONFIRM="--assume-yes"
 else

scripts/install_open3d.bash

@@ -1,7 +1,21 @@
 #!/usr/bin/env bash
 set -e
 
-SUDO=${SUDO:=sudo} # SUDO=command in docker (running as root, sudo not available)
+command_exists() {
+  command -v "$@" >/dev/null 2>&1
+}
+
+user_can_sudo() {
+  command_exists sudo || return 1
+  ! LANG= sudo -n -v 2>&1 | grep -q "may not run sudo"
+}
+
+if user_can_sudo; then
+SUDO="sudo"
+else
+SUDO="" # To support docker environment
+fi
+
 if [ "$1" == "assume-yes" ]; then
     APT_CONFIRM="--assume-yes"
 else