Differences

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--- software:start [2019/02/25 21:34]
frey
+++ software:start [2019/02/25 22:07] (current)
frey [Putting it all together]
@@ Line 71: / Line 71: @@
 ===== Organizing software =====
-Given the different directories used by Unix/Linux to hold the various components of software and the ''PATH'' and ''LD_LIBRARY_PATH'' variables' ability to alter where the shell and runtime linker look to find executables and libraries, you have all the tools necessary to organize the software you maintain.
+Given the different directories used by Unix/Linux to hold the various components of software and the ''PATH'' and ''LD_LIBRARY_PATH'' variables' ability to alter where the shell and runtime linker look to find executables and libraries, you have all the tools necessary to organize the software you maintain:  any directory can have the ''bin'', ''lib64'', ''include'', et al. directories created within it as in ''/usr/local''.  Adopting the same filesystem layout makes clear the purpose of each file therein.  Adding ''<prefix>/bin'' to the ''PATH'' makes any executables present within that directory available to you.
+==== Source code ====
+Many Linux distributions have a ''/usr/local/src'' directory present.  This directory is meant to hold source code packages that are built and installed under ''/usr/local''.  For any software directory you manage, adopt the same strategy:
+  * If the software directory holds components of a single source package, unpack that source code as the ''<prefix>/src'' directory
+  * For a software directory containing components from multiple source packages (like ''/usr/local'') unpack each constituent source package as a directory under the ''<prefix>/src'' directory
+==== Versioning ====
+It is often the case when maintaining software that more than one //version// of the software must be present.  Each distinct //version// implies a different rendition of the software source code.  //Variants// of a version of the software may be present when, for example, different compilers are used to build the same version of the software.
+In these cases, installation into a common software directory like ''/usr/local'' is inadvisable, since a single version or variant of the software is present and will likely change as time goes by.  Using a unique software directory for each version or variant — and adopting the Unix/Linux filesystem layout therein — keeps each distinct copy of the software isolated from the others, and is easily added to the shell by altering the ''PATH'' and ''LD_LIBRARY_PATH'' variables, for example.
+==== Putting it all together ====
+I need to manage multiple versions and variants of the Open MPI tools.  To start, I create a directory that will hold all of the versions and variants I build:
+<code bash>
+$ mkdir -p ~/programs/open-mpi
+$ cd ~/programs/open-mpi
+</code>
+I will download the official source code and store each version I download in a directory — if at any time I need to build another variant of that version, I will have that version's source code available:
+<code bash>
+$ mkdir attic
+$ cd attic
+$ wget 'https://download.open-mpi.org/release/open-mpi/v3.1/openmpi-3.1.3.tar.bz2'
+$ ls -l
+total 1
+-rw-r--r-- 1 frey everyone 9442937 Oct 29 17:51 openmpi-3.1.3.tar.bz2
+</code>
+To build a variant of the 3.1.3 version with standard system compilers, I'll create a directory and unpack the source code inside it:
+<code bash>
+$ cd ..
+$ mkdir 3.1.3
+$ cd 3.1.3
+$ tar -xf ../attic/openmpi-3.1.3.tar.bz2
+$ mv openmpi-3.1.3 src
+$ cd src
+</code>
+Open MPI uses the GNU Autoconf tools, so configuring the build to install the software into this variant's software directory is very straightforward:
+<code bash>
+$ ./configure --prefix="$(realpath ~/programs/open-mpi/3.1.3)"
+     :
+$ make
+$ make install
+$ cd ..
+$ pwd
+/home/1001/programs/open-mpi/3.1.3
+$ ls -l bin
+total 474
+-rwxr-xr-x 1 frey sysadmin  1740 Oct  8 11:04 aggregate_profile.pl
+lrwxrwxrwx 1 frey sysadmin    12 Oct  8 11:05 mpic++ -> opal_wrapper
+lrwxrwxrwx 1 frey sysadmin    12 Oct  8 11:05 mpicc -> opal_wrapper
+lrwxrwxrwx 1 frey sysadmin    12 Oct  8 11:05 mpiCC -> opal_wrapper
+    :
+lrwxrwxrwx 1 frey sysadmin    12 Oct  8 11:05 shmemcxx -> opal_wrapper
+lrwxrwxrwx 1 frey sysadmin    12 Oct  8 11:05 shmemfort -> opal_wrapper
+lrwxrwxrwx 1 frey sysadmin     6 Oct  8 11:05 shmemrun -> mpirun
+</code>