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Run Commands As A User

22 Jul 2020

Create Dockerfile

# Build from base image
FROM ubuntu:latest

# Add a user named chris
RUN useradd -ms /bin/bash  chris

# Create a file
RUN touch before_user_command.txt

# Change to user "Chris"
USER chris

# Create a file
RUN touch ~/after_user_command.txt

Build Image From Dockerfile

Build the Dockerfile (docker build) in the current directory (.) and call the image chrisalbon/big-project:user-example (--tag chrisalbon/big-project:user-example).

docker build --tag chrisalbon/big-project:user-example .

Sending build context to Docker daemon  4.608kB
Step 1/5 : FROM ubuntu:latest
 ---> 1e4467b07108
Step 2/5 : RUN useradd -ms /bin/bash  chris
 ---> Using cache
 ---> e4b9e6ef4c5a
Step 3/5 : RUN touch before_user_command.txt
 ---> Using cache
 ---> e1e32b44be33
Step 4/5 : USER chris
 ---> Using cache
 ---> 069afa90c79d
Step 5/5 : RUN touch ~/after_user_command.txt
 ---> Running in bb67374528f9
Removing intermediate container bb67374528f9
 ---> 2fb9292fcd9b
Successfully built 2fb9292fcd9b
Successfully tagged chrisalbon/big-project:user-example

Run Docker Container From Image

Start and create (docker run) an interative (-it) Docker container from the image called chrisalbon/big-project:user-example. Remove the container after it stops (-rm)

docker run --rm -it chrisalbon/big-project:user-example

[email protected]:/$

View Root Directory

View all files and folders (ls) that displays using long format and shows hidden files (-al) in the root directory.

ls -al

total 56
drwxr-xr-x   1 root root 4096 Aug 25 02:10 .
drwxr-xr-x   1 root root 4096 Aug 25 02:10 ..
-rwxr-xr-x   1 root root    0 Aug 25 02:10 .dockerenv
-rw-r--r--   1 root root    0 Aug 25 02:04 before_user_command.txt
lrwxrwxrwx   1 root root    7 Jul 20 14:43 bin -> usr/bin
drwxr-xr-x   2 root root 4096 Apr 15 11:09 boot
drwxr-xr-x   5 root root  360 Aug 25 02:10 dev
drwxr-xr-x   1 root root 4096 Aug 25 02:10 etc
drwxr-xr-x   1 root root 4096 Aug 25 02:04 home
lrwxrwxrwx   1 root root    7 Jul 20 14:43 lib -> usr/lib
lrwxrwxrwx   1 root root    9 Jul 20 14:43 lib32 -> usr/lib32
lrwxrwxrwx   1 root root    9 Jul 20 14:43 lib64 -> usr/lib64
lrwxrwxrwx   1 root root   10 Jul 20 14:43 libx32 -> usr/libx32
drwxr-xr-x   2 root root 4096 Jul 20 14:43 media
drwxr-xr-x   2 root root 4096 Jul 20 14:43 mnt
drwxr-xr-x   2 root root 4096 Jul 20 14:43 opt
dr-xr-xr-x 711 root root    0 Aug 25 02:10 proc
drwx------   2 root root 4096 Jul 20 14:57 root
drwxr-xr-x   1 root root 4096 Jul 24 14:38 run
lrwxrwxrwx   1 root root    8 Jul 20 14:43 sbin -> usr/sbin
drwxr-xr-x   2 root root 4096 Jul 20 14:43 srv
dr-xr-xr-x  13 root root    0 Aug 25 02:07 sys
drwxrwxrwt   2 root root 4096 Jul 20 14:57 tmp
drwxr-xr-x   1 root root 4096 Jul 20 14:43 usr
drwxr-xr-x   1 root root 4096 Jul 20 14:57 var

Notice that root owns before_user_command.txt.

View User Home Directory

View all files and folders (ls) that displays using long format and shows hidden files (-al) in the directory home/chris/.

ls -al home/chris/

total 20
drwxr-xr-x 1 chris chris 4096 Aug 25 02:10 .
drwxr-xr-x 1 root  root  4096 Aug 25 02:04 ..
-rw-r--r-- 1 chris chris  220 Feb 25 12:03 .bash_logout
-rw-r--r-- 1 chris chris 3771 Feb 25 12:03 .bashrc
-rw-r--r-- 1 chris chris  807 Feb 25 12:03 .profile
-rw-r--r-- 1 chris chris    0 Aug 25 02:10 after_user_command.txt

Notice that chris owns after_user_command.txt.