Add lock script

lock.sh

@@ -0,0 +1,46 @@
+#!/bin/bash
+
+LOCKDIR="/tmp/snapshotslocks/"
+
+[ ! -d "$LOCKDIR" ] && mkdir -p "$LOCKDIR"
+
+createlock() {
+    LOCKNAME=$1
+    [ -f "$LOCKDIR/$LOCKNAME.lock" ] && exit 1
+    touch "$LOCKDIR/$LOCKNAME.lock"
+    exit 0
+}
+
+deletelock() {
+    LOCKNAME=$1
+    [ ! -f "$LOCKDIR/$LOCKNAME.lock" ] && exit 1
+    rm "$LOCKDIR/$LOCKNAME.lock"
+    exit 0
+}
+
+haslock() {
+    if ls $LOCKDIR/* 1> /dev/null 2>&1; then
+        exit 0
+    else
+        exit 1
+    fi
+}
+
+case $1 in
+    lock)
+        createlock $2
+        ;;
+    unlock)
+        deletelock $2
+        ;;
+    haslock)
+        haslock
+        ;;
+    show)
+        ls $LOCKDIR
+        ;;
+    *)
+        echo "What is $1" >&2
+        exit 1
+esac
+