# Modify global variable in grafana

**URL:** <https://community.grafana.com/t/modify-global-variable-in-grafana/44538>\
**Category:** Prometheus\
**Tags:** templating\
**Created:** [March 15, 2021, 4:04pm UTC](https://community.grafana.com/t/modify-global-variable-in-grafana/44538 "2021-03-15T16:04:23Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![luca97vale](https://avatars.discourse-cdn.com/v4/letter/l/a6a055/32.png) [@luca97vale](https://community.grafana.com/u/luca97vale)\
**Post date:** [March 15, 2021, 4:04pm UTC](https://community.grafana.com/t/modify-global-variable-in-grafana/44538/1 "2021-03-15T16:04:23Z")

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Hi everyone,  
I want to get the {\_\_user.login} value using prometheus as data source. What is the correct metric to get the value? I would like to create a variable modifying the {\_\_user.login} variable using regex field.  
Is there any way to do this?