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Thanks for any help given!

I am new to Docker (Using 17.06.2-ee-10), and currently I am using it on Windows Server 2016, running windowsservercore image. My question is simple.

In my dockerfile I have

ARG destpath=C:\path\ ARG javafile=java.exe

What I want to do is make another variable

ARG javapath=$destpath$javafile

This is where I run into problems.

If I RUN echo %javapath% it returns $destpath$javafile (And sometimes not even that)

It never takes the added variables together. I have tried a few different things, such as making (ARG javapath=%destpath%%javafile%.) or trying to escape the "\" characters on the path. But nothing works.

I am a beginner and unsure if I need to be more detailed in my question, or dockerfile just doesn't allow what I am trying to do. If you need more clarification please let me know.

Thanks

Arthur

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Putting curly braces around your variables, instead of just in potentially ambiguous cases, can be considered good programming practice. So, try the curly braces. This worked for me.

UPDATED ANSWER:

Sorry, I should have tested the values that YOU provided. Yeah, to make it work I had to wrap C:\path\ in single quotes:

FROM centos:latest ARG destpath='C:\path\' ARG javafile=java.exe ARG javapath=${destpath}${javafile} RUN echo $javapath

Result:

$ docker build -t temp . Sending build context to Docker daemon 2.048kB Step 1/5 : FROM centos:latest ---> e934aafc2206 Step 2/5 : ARG destpath='C:\path\' ---> Running in 61f1aa0ea477 Removing intermediate container 61f1aa0ea477 ---> f49332bb07f9 Step 3/5 : ARG javafile=java.exe ---> Running in 7f965bea7edf Removing intermediate container 7f965bea7edf ---> b1d66e9b07ff Step 4/5 : ARG javapath=${destpath}${javafile} ---> Running in 9cfb4e2274f3 Removing intermediate container 9cfb4e2274f3 ---> 65dc408e384b Step 5/5 : RUN echo $javapath ---> Running in 7906c930caef C:\path\java.exe ##################################### there you go Removing intermediate container 7906c930caef ---> 887ef91def32 Successfully built 887ef91def32 Successfully tagged temp:latest

OLD ANSWER:

FROM centos:latest ARG destpath=hello ARG javafile=world ARG javapath=${destpath}${javafile} RUN echo $javapath

My result was as following:

$ docker build -t temp . Step 1/5 : FROM centos:latest ---> e934aafc2206 Step 2/5 : ARG destpath=hello ---> Running in 30f047122373 Removing intermediate container 30f047122373 ---> 582d3a801fd0 Step 3/5 : ARG javafile=world ---> Running in 78817656b729 Removing intermediate container 78817656b729 ---> a3afa410e42e Step 4/5 : ARG javapath=${destpath}${javafile} ---> Running in 8baf8c862572 Removing intermediate container 8baf8c862572 ---> 1a9c012e4d57 Step 5/5 : RUN echo $javapath ---> Running in 48ee08e6452d helloworld ############################################## there it is Removing intermediate container 48ee08e6452d ---> 9d72ba2aab67 Successfully built 9d72ba2aab67 Successfully tagged temp:latest

P.S. If this doesn't work, it's windows' fault.

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2 Comments

Thank you for your help. Unfortunately it doesn't work when I try it, my echo $javapath results on $javapath and echo %javapath% results in ${destpath}${javafile}. Seems to be a windows issue, and I have yet to see a solution/example online.
windows is not the best thing to use with... everything when you do programming...

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