grml-screen: output errors to stderr

[grml-scripts-core.git] / usr_bin / grml-screen

diff --git a/usr_bin/grml-screen b/usr_bin/grml-screen
index cd40503..a33131a 100755 (executable)
--- a/usr_bin/grml-screen
+++ b/usr_bin/grml-screen
@@ -4,7 +4,6 @@
 # Authors:       grml-team (grml.org), (c) Michael Prokop <mika@grml.org>
 # Bug-Reports:   see http://grml.org/bugs/
 # License:       This file is licensed under the GPL v2.
-# Latest change: Mit Mär 21 15:39:00 CET 2007 [mika]
 ################################################################################
 
 # export variable USER for use withing GNU screen:
@@ -15,6 +14,49 @@
   sudo chmod 660       $TTY
   sudo chown $USER.tty $TTY
 
+# FIXME: fix for screen race-conditions
+PID_FILE_="/var/lock/grml-screen"
+PID_FILE_CREATED_="false"
+MY_PID_="$$"
+if [ ! -d "/var/run/screen/S-$USER" ]; then
+    # no /var/run/screen/S-$USER and possible no /var/run/screen either -> locking
+    for i in `seq 40`; do   # 40*0.25 = 10 seconds
+        if lockfile-create --retry 0 $PID_FILE_; then
+            echo $MY_PID_ >$PID_FILE_
+            PID_FILE_CREATED_="true"
+            break
+        else
+            PID_FILE_CREATED_="error"
+        fi
+        sleep 0.25
+    done
+fi
+if [ $PID_FILE_CREATED_ = "true" ]; then
+    # FORK BEGIN
+    (
+        for i in `seq 40`; do   # 40*0.25 = 10 seconds
+            if [ ! -d "/var/run/screen/S-$USER" ]; then
+                sleep 0.25  # educated guess
+            else
+                break
+            fi
+        done
+        if [ `cat $PID_FILE_` = $MY_PID_ ]; then
+            rm $PID_FILE_
+            lockfile-remove $PID_FILE_
+        fi
+    )&
+    # FORK END
+elif [ $PID_FILE_CREATED_ = "error" ]; then
+    SLEEP_TIME_="$(( $$ % 5 * 5 + 5 ))"
+    echo "grml-screen: Error could not create lockfile! (sleeping for $SLEEP_TIME_)" >&2
+    sleep $SLEEP_TIME_
+elif [ $PID_FILE_CREATED_ = "false" ]; then
+    echo "nothing to do" &>/dev/null
+else
+    echo "grml-screen: internal error - PID_FILE_CREATED_ == \"$PID_FILE_CREATED_\"" >&2
+fi
+
 # now run screen with config
   cd $HOME     # important for e.g. hardcopy-feature
   # do we have a utf8 enabled terminal?