Appending output of a Batch file To log file

I have a batch file开发者_如何学Go which calls a java program.

The output is redirected to a log file in the same directory. However the log file is replaced everytime the batch file is run...

I would like to keep the old outputs in the log file and always append the new output to the log file.

Instead of using ">" to redirect like this:

java Foo > log

use ">>" to append normal "stdout" output to a new or existing file:

java Foo >> log

However, if you also want to capture "stderr" errors (such as why the Java program couldn't be started), you should also use the "2>&1" tag which redirects "stderr" (the "2") to "stdout" (the "1"). For example:

java Foo >> log 2>&1 

This is not an answer to your original question: "Appending output of a Batch file To log file?"

For reference, it's an answer to your followup question: "What lines should i add to my batch file which will make it execute after every 30mins?"

(But I would take Jon Skeet's advice: "You probably shouldn't do that in your batch file - instead, use Task Scheduler.")

Timeout:

• timeout command 1
• timeout command 2

Example (1 second):

TIMEOUT /T 1000 /NOBREAK

Sleep:

• sleep command (if sleep.exe is installed)

Example (1 second):

sleep -m 1000

Alternative methods:

• Sleeping in a batch file
• batch script, put to sleep until certain time

Here's an answer to your 2nd followup question: "Along with the Timestamp?"

Create a date and time stamp in your batch files

Example:

echo *** Date: %DATE:/=-% and Time:%TIME::=-% *** >> output.log

Use log4j in your java program instead. Then you can output to multiple media, create rolling logs, etc. and include timestamps, class names and line numbers.

It's also possible to use java Foo | tee -a some.log. it just prints to stdout as well. Like:

user at Computer in ~
$ echo "hi" | tee -a foo.txt
hi

user at Computer in ~
$ echo "hello" | tee -a foo.txt
hello

user at Computer in ~
$ cat foo.txt
hi
hello