# Replace branch name backslash

**URL:** <https://drone.discourse.group/t/replace-branch-name-backslash/10369>\
**Category:** Drone Support\
**Created:** [September 3, 2019, 7:20am UTC](https://drone.discourse.group/t/replace-branch-name-backslash/10369 "2019-09-03T07:20:58Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![songtianyi](https://avatars.discourse-cdn.com/v4/letter/s/b5ac83/32.png) [@songtianyi](https://drone.discourse.group/u/songtianyi)\
**Post date:** [September 3, 2019, 7:20am UTC](https://drone.discourse.group/t/replace-branch-name-backslash/10369/1 "2019-09-03T07:20:59Z")

</div>

```auto
docker build -t hub.sky-cloud.net/nap/nap-executor:${DRONE_BRANCH//[^a-zA-Z0-9.]/-}_build-${DRONE_BUILD_NUMBER} .

```

this is what I’m trying to do. error msg as following

```auto
+ docker build -t hub.sky-cloud.net/nap/nap-executor:release/1.7.0_build-27 .
invalid argument "hub.sky-cloud.net/nap/nap-executor:release/1.7.0_build-27" for "-t, --tag" flag: invalid reference format
See 'docker build --help'.

```

It has been tested in localhost.

```auto
[root@drone nap-executor]# echo ${DRONE_BRANCH//[^a-zA-Z0-9.]/-}
release-1.7.0
[root@drone nap-executor]#

```