variable containing output of docker exec command malaligned

Question

I am trying to run bash inside docker container using docker exec bash -c and store its output on the host(not the container) by echo'ing something which will be used in conditional statement. I could be echo'ing anything like ip hostname or just a string. Problem is that the echo output

[root@localhost ~]# var1=$(docker exec -t test_masternode1 bash -c 'echo 1')
[root@localhost ~]# echo $var1
1
[root@localhost ~]# declare -p var1
"eclare -- var1="1
[root@localhost ~]# var2=1
[root@localhost ~]# declare -p var2
declare -- var2="1"
[root@localhost ~]# echo $var2
1
[root@localhost ~]# if [ "$var1" == "$var2" ];then echo "same";else echo "not same";fi
not same
[root@localhost ~]#

As you can see var1 and var2 both echo 1 but the if-else condition is failing. Also the variable declaration output is maligned. Something is messing up the output from docker container to host, not sure what that is

I also tried another docker image from Ubuntu. Example above was from centos7

[root@localhost ~]# var3=`docker run -t ubuntu bash -c 'echo 1'`
[root@localhost ~]# declare -p var3
"eclare -- var3="1
[root@localhost ~]#

Answer 1

The data comes back with a carriage return from Docker. The carriage return, when outputted, causes the cursor to move to the beginning of the line. Hence the slightly odd-looking output when you display the value of your variable. This seems to be (or have been) an issue for others as well, as is evident from this GitHub issue.

To remove any carriage returns from the data, pass it through tr -d '\r':

var1=$(docker exec -t test_masternode1 bash -c 'echo 1' | tr -d '\r')

... or simply run your command without the -t option.