Merge pull request #14 from KrustyHack/master

Adding when-down and until-error.

Author: skx

README.md

@@ -378,7 +378,7 @@ Trivial (ba)sh alternatives:
 when-up
 -------
 
-Waits until a given host is online (determined by ping until executing a given command
+Waits until a given host is online (determined by ping until executing a given command)
 
 Example:
 
@@ -393,6 +393,40 @@ Alternatives:
 
 
 
+until-error
+-------------
+
+Repeat the specific command until it fails - run at least once
+always.
+
+Example:
+
+         ./until-error ssh example.com -l root -i ~/.ssh/example.com.key
+
+Trivial (ba)sh alternatives:
+
+* while true ; do $cmd; done
+* watch -n 2 $cmd
+
+
+
+when-down
+-------
+
+Waits until a given host is down
+
+Example:
+
+     $ ./when-down 1.2.3.4 echo "down"
+     Waiting for 1.2.3.4 to get down...
+     down
+
+Alternatives:
+
+* `until-error ping -c 1 -W 1 1.2.3.4; echo "down"`
+
+
+
 which-shell
 -----------
 

until-error

@@ -0,0 +1,17 @@
+#!/bin/sh
+#
+# About
+# -----
+# Repeat the command until it fails
+#
+
+"$@"
+
+#
+#  If the status code was zero then repeat.
+#
+while [ $? -eq 0 ]; do
+    "$@"
+done
+
+

when-down

@@ -0,0 +1,32 @@
+#!/bin/sh
+#
+# Wait until a given host is down (determined by ping) then execute the
+# given command
+#
+# Usage:
+# ./when-down HOST COMMAND...
+#
+# Example
+# ./when-down 1.2.3.4 ssh 1.2.3.4
+#
+
+
+#
+#  Ensure we received the correct number of arguments.
+#
+if [ $# -lt 2 ]; then
+    echo "Usage: when-down HOST COMMAND..."
+    exit 1
+fi
+
+HOST=$1
+
+echo "Waiting for $HOST to get down..."
+
+true
+while [ $? -ne 1 ]; do
+    ping -c 1 -W 1 $HOST >/dev/null
+done
+
+shift
+$*