> For the complete documentation index, see [llms.txt](https://n-saikiran.gitbook.io/jenkins/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://n-saikiran.gitbook.io/jenkins/5-jenkins-advanced/51-jenkins-challenges.md).

# 5.1Jenkins Challenges

hudson CI: how to delete all jobs?

Q: I have about 100 jobs on my hudson CI, possible to mass delete them ?

A: The easiest way, IMHO, would be to use script. Go to <http://your.hudson.url/script/>

Delete jobs by running in Older versions(1.x):

> for(j in hudson.model.Hudson.theInstance.getProjects()) {
>
> ```
> j.delete\(\);
> ```
>
> }

And this way gives you an option to easily use condition to filter out jobs to delete.

FOR JENKINS Current versions (2.x):

> for(j in jenkins.model.Jenkins.theInstance.getAllItems()) {
>
> ```
> j.delete\(\)
> ```
>
> }

Q: How to reset build number in jenkins?

A: Can be easier done from groovy script console . Go to <http://your-jenkins-server/script> In script window enter:

> item = Jenkins.instance.getItemByFullName("your-job-name-here")
>
> //THIS WILL REMOVE ALL BUILD HISTORY
>
> item.builds.each() { build ->
>
> build.delete()
>
> }
>
> item.updateNextBuildNumber(1)

OR

> echo "deleting all builds of ${jobName}" item = Jenkins.instance.getItemByFullName("${jobName}") for (build in item.builds){ build.delete(); } item.updateNextBuildNumber(1)

For ALL PROJECTS

> Jenkins.instance.allItems.each() {
>
> item -> item.builds.each() {
>
> ```
> build -&gt; build.delete\(\)
> ```
>
> }
>
> item.updateNextBuildNumber(1)
>
> }