I was trying to install some software from source today. After dicking around for a full day last week trying to port it’s build chain to Bazel, I decided to just install the build toolchain it expects.<\/p>\n
I install Cmake, and try to build my program. No dice! This source file requires cmake version 2.8.12, and CentOS 7 comes with 2.8.11. Ergh. So, I go back to source, and grab and make the latest cmake. A quick make, make install, and I go back to the original directory and… get the same error message?<\/p>\n
\/cmake .\r\nCMake Error at CMakeLists.txt:1 (cmake_minimum_required):\r\n CMake 2.8.12 or higher is required. You are running version 2.8.11\r\n\r\n<\/pre>\nWhat can this be? Did it not install? I make clean, make install again, and this time I search for where it’s installing. \/usr\/local\/bin\/cmake ; It seems to work. It’s in path. I run ‘which cmake’ and it tells me ” \/usr\/local\/bin\/cmake”, as I expect. I run directly from that path, and check the version; 3.2.2, as I expected. What gives? Why does simply running it not give me the expected results? I throw strace at it; The top line of strace shows the correct path:<\/p>\n
execve(\"\/usr\/local\/bin\/cmake\", [\"cmake\"], [\/* 26 vars *\/]) = 0<\/pre>\nAt this point, I’m fairly stumped. Clearly, the old executable still exists, so I search my path for it; The old version of cmake is in \/usr\/bin. I then wonder at what could be causing the redirection, so I launch a new terminal, type cmake –version… and I get the correct result! Launching bash as a subshell also gives me what I want. So, what’s wrong with my initial shell?<\/p>\n
At this point, I was fairly stumped, so I asked my dad, an old unix hand, and he pointed me to the ‘hash’ builtin. Bash keeps a dictionary of commands to their full pathnames; Presumably for speed, as doing several directory listings for each command would be wasteful, even with all of the PATH directories in ram.<\/p>\n
The solution is simply to call ‘hash cname’ or ‘hash -r’ to cause bash to redo the dictionary entry for cname, or for everything, respectively.<\/p>\n","protected":false},"excerpt":{"rendered":"
I was trying to install some software from source today. After dicking around for a full day last week trying to port it’s build chain to Bazel, I decided to just install the build toolchain it expects. I install Cmake, and try to build my program. No dice! This source file requires cmake version 2.8.12, … Continue reading When is a cmake not a cmake?<\/span>