In a Dockerfile How to update PATH environment variable

Question

I have a dockerfile that download and builds GTK from source  but the following line is not updating my image s environment variable   RUN PATH   opt gtk bin  PATH  RUN export PATH   I read that that I should be using ENV to set environment values  but the following instruction doesn t seem to work either   ENV PATH  opt gtk bin  PATH  This is my entire Dockerfile   FROM ubuntu RUN apt-get update RUN apt-get install -y golang gcc make wget git libxml2-utils libwebkit2gtk-3 0-dev libcairo2 libcairo2-dev libcairo-gobject2 shared-mime-info libgdk-pixbuf2 0-  libglib2-  libatk1 0-  libpango1 0-  xserver-xorg xvfb    Downloading GTKcd RUN wget http   ftp gnome org pub gnome sources gtk  3 12 gtk -3 12 2 tar xz RUN tar xf gtk -3 12 2 tar xz RUN cd gtk -3 12 2    Setting environment variables before running configure RUN CPPFLAGS  -I opt gtk include  RUN LDFLAGS  -L opt gtk lib  RUN PKG CONFIG PATH   opt gtk lib pkgconfig  RUN export CPPFLAGS LDFLAGS PKG CONFIG PATH RUN   configure --prefix  opt gtk RUN make RUN make install    running ldconfig after make install so that the newly installed libraries are found  RUN ldconfig    Setting the LD LIBRARY PATH environment variable so the systems dynamic linker can find the newly installed libraries  RUN LD LIBRARY PATH   opt gtk lib     Updating PATH environment program so that utility binaries installed by the various libraries will be found  RUN PATH   opt gtk bin  PATH  RUN export LD LIBRARY PATH PATH    Collecting garbage RUN rm -rf gtk -3 12 2 tar xz    creating go code root RUN mkdir gocode RUN mkdir gocode src RUN mkdir gocode bin RUN mkdir gocode pkg    Setting the GOROOT and GOPATH enviornment variables  any commands created are automatically added to PATH RUN GOROOT  usr lib go RUN GOPATH  root gocode RUN PATH  GOPATH bin  PATH RUN export GOROOT GOPATH PATH

User · Accepted Answer

You can use Environment Replacement in your Dockerfile as follows   ENV PATH   opt gtk bin   PATH

User · Answer

Although the answer that Gunter posted was correct  it is not different than what I already had posted  The problem was not the ENV directive  but the subsequent instruction RUN export  PATH  There s no need to export the environment variables  once you have declared them via ENV in your Dockerfile    As soon as the RUN export     lines were removed  my image was built successfully

User · Answer

I mentioned this in response to the selected answer  but it was suggested to make it more prominent as an answer of its own  It should be noted that ENV PATH  quot  opt gtk bin   PATH  quot    may not be the same as ENV PATH  quot  opt gtk bin  PATH quot    The former  with curly brackets  might provide you with the host s PATH  The documentation doesn t suggest this would be the case  but I have observed that it is  This is simple to check just do RUN echo  PATH and compare it to RUN echo   PATH

User · Answer

This is discouraged  if you want to create distribute a clean Docker image   since the PATH variable is set by  etc profile script  the value can be overridden   head  etc profile   if     id -u   -eq 0    then   PATH   usr local sbin  usr local bin  usr sbin  usr bin  sbin  bin  else   PATH   usr local bin  usr bin  bin  usr local games  usr games  fi export PATH   At the end of the Dockerfile  you could add   RUN echo  export PATH  PATH   gt   etc environment   So PATH is set for all users

[docker] In a Dockerfile, How to update PATH environment variable?

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