# What is logstash instance? **URL:** \ **Category:** Logstash\ **Tags:** elastic-stack-machine-learning, elastic-stack-alerting, elastic-stack-monitoring, elastic-stack-security\ **Created:** [October 19, 2023, 7:00am UTC](https://discuss.elastic.co/t/what-is-logstash-instance/345357 "2023-10-19T07:00:30Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Nghia\_D\_ng](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/nghia_d_ng/32/123483_2.png) [@Nghia\_D\_ng](https://discuss.elastic.co/u/Nghia_D_ng)\ **Post date:** [October 19, 2023, 7:00am UTC](https://discuss.elastic.co/t/what-is-logstash-instance/345357/1 "2023-10-19T07:00:30Z")
I want to know what a logstash instance is? Is it a self-generated .conf file? Which command should I use to check which instances are running? ---
**Author:** ![carly.richmond](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/carly.richmond/32/104935_2.png) [@carly.richmond](https://discuss.elastic.co/u/carly.richmond)\ **Post date:** [October 19, 2023, 9:00am UTC](https://discuss.elastic.co/t/what-is-logstash-instance/345357/2 "2023-10-19T09:00:35Z")
Hi @Nghia_D_ng, An instance of Logstash would be a single running instance processing events from a source with the specified pipeline transformations. The `.conf` file is the configuration for your instance of Logstash, including the inputs, outputs and transformations. I would recommend having a look at the [How it Works](https://www.elastic.co/guide/en/logstash/8.10/pipeline.html) and [Setup](https://www.elastic.co/guide/en/logstash/8.10/setup-logstash.html) portions of the documentation for a more detailed overview. Hope that helps! ---
**Author:** ![Nghia\_D\_ng](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/nghia_d_ng/32/123483_2.png) [@Nghia\_D\_ng](https://discuss.elastic.co/u/Nghia_D_ng)\ **Post date:** [October 19, 2023, 9:14am UTC](https://discuss.elastic.co/t/what-is-logstash-instance/345357/3 "2023-10-19T09:14:25Z")
HI @carly.richmond , I use to check which instances are running? ---
**Author:** ![carly.richmond](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/carly.richmond/32/104935_2.png) [@carly.richmond](https://discuss.elastic.co/u/carly.richmond)\ **Post date:** [October 19, 2023, 9:16am UTC](https://discuss.elastic.co/t/what-is-logstash-instance/345357/4 "2023-10-19T09:16:53Z")
Hi @Nghia_D_ng, You would check using the OS-specific process command on your machine. For example, on linux it would be something like the below: `ps -a | grep logstash` Hope that helps! ---
**Author:** ![Nghia\_D\_ng](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/nghia_d_ng/32/123483_2.png) [@Nghia\_D\_ng](https://discuss.elastic.co/u/Nghia_D_ng)\ **Post date:** [October 19, 2023, 9:22am UTC](https://discuss.elastic.co/t/what-is-logstash-instance/345357/5 "2023-10-19T09:22:15Z")
Hi @carly.richmond , I use CentOS, this command does not work for you ![image](https://us1.discourse-cdn.com/elastic/original/3X/9/2/92c7ca7c26942302ffdc9e0c203f8fe0119c1175.png) ---
**Author:** ![carly.richmond](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/carly.richmond/32/104935_2.png) [@carly.richmond](https://discuss.elastic.co/u/carly.richmond)\ **Post date:** [October 19, 2023, 9:29am UTC](https://discuss.elastic.co/t/what-is-logstash-instance/345357/6 "2023-10-19T09:29:53Z")
@Nghia_D_ng if there is no output from the command the grep command doesn't find logstash within the output from the piped `ps` command. There are several different commands for finding processes including `top` and `pgrep` [as covered here](https://www.cyberciti.biz/faq/show-all-running-processes-in-linux/). Have you started Logstash on your machine [using the instructions in the docs](https://www.elastic.co/guide/en/logstash/current/running-logstash-command-line.html)? ---
**Author:** ![carly.richmond](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/carly.richmond/32/104935_2.png) [@carly.richmond](https://discuss.elastic.co/u/carly.richmond)\ **Post date:** [October 19, 2023, 9:30am UTC](https://discuss.elastic.co/t/what-is-logstash-instance/345357/7 "2023-10-19T09:30:45Z")
It could also be the process is running as a different user, in which case you may need to use the `-aux` options. ---
**Author:** ![Nghia\_D\_ng](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/nghia_d_ng/32/123483_2.png) [@Nghia\_D\_ng](https://discuss.elastic.co/u/Nghia_D_ng)\ **Post date:** [October 19, 2023, 9:43am UTC](https://discuss.elastic.co/t/what-is-logstash-instance/345357/8 "2023-10-19T09:43:21Z")
Hi @carly.richmond , ps -aux|grep logstash is this? ---
**Author:** ![Nghia\_D\_ng](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/nghia_d_ng/32/123483_2.png) [@Nghia\_D\_ng](https://discuss.elastic.co/u/Nghia_D_ng)\ **Post date:** [November 2, 2023, 4:17am UTC](https://discuss.elastic.co/t/what-is-logstash-instance/345357/9 "2023-11-02T04:17:25Z")
HI @carly.richmond , I have 2 logstash instances, how do I start each instance individually? Thanks you! ---
**Author:** ![Nghia\_D\_ng](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/nghia_d_ng/32/123483_2.png) [@Nghia\_D\_ng](https://discuss.elastic.co/u/Nghia_D_ng)\ **Post date:** [November 2, 2023, 4:23am UTC](https://discuss.elastic.co/t/what-is-logstash-instance/345357/10 "2023-11-02T04:23:50Z")
Hi @carly.richmond Please help me! ---
**Author:** ![carly.richmond](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/carly.richmond/32/104935_2.png) [@carly.richmond](https://discuss.elastic.co/u/carly.richmond)\ **Post date:** [November 2, 2023, 2:50pm UTC](https://discuss.elastic.co/t/what-is-logstash-instance/345357/11 "2023-11-02T14:50:49Z")
Hi @Nghia_D_ng, Do you mean you want to run multiple instances? Or do you want to use [multiple pipelines](https://www.elastic.co/guide/en/logstash/master/multiple-pipelines.html#multiple-pipelines) within a single process? ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [November 30, 2023, 2:50pm UTC](https://discuss.elastic.co/t/what-is-logstash-instance/345357/12 "2023-11-30T14:50:54Z")
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