src/doc/en/developer/portability_testing.rst: Reformat some examples

Author: Matthias Koeppe

src/doc/en/developer/portability_testing.rst

@@ -9,7 +9,7 @@ Testing on Multiple Platforms
 =============================
 
 Sage is intended to build and run on a variety of platforms,
-including all major Linux distributions, as well as MacOS, and
+including all major Linux distributions, as well as macOS, and
 Windows (with WSL).
 
 There is considerable variation among these platforms.
@@ -128,9 +128,9 @@ Typical Docker images provide minimal installations of packages only::
 
 As you can see above, the image ``ubuntu:latest`` has neither a Python nor
 a GCC installed, which are among the build prerequisites of Sage.  We
-need to install them using the distribution's package manager first.
+need to install them using the Linux distribution's package manager first.
 
-Sage facilitates testing various distributions on Docker as follows.
+Sage facilitates testing various Linux distributions on Docker as follows.
 
 Discovering the system's package system
 ---------------------------------------
@@ -142,7 +142,7 @@ Discovering the system's package system
 
 Let's install gcc, hoping that the Ubuntu package providing it is
 simply named ``gcc``.  If we forgot what the package manager on
-Debian-derived distributions is called, we can ask Sage for a
+Debian-derived Linux distributions is called, we can ask Sage for a
 reminder::
 
   root@39d693b2a75d:/sage# build/bin/sage-print-system-package-command debian install gcc
@@ -190,7 +190,8 @@ example, the file ``build/pkgs/_prereq/distros/debian.txt`` contains the followi
 From this information, we know that we can use the following command
 on our container to install the necessary build prerequisites::
 
-  root@39d693b2a75d:/sage# apt-get install binutils make m4 perl python3 tar bc gcc g++ ca-certificates
+  root@39d693b2a75d:/sage# apt-get install binutils make m4 perl python3 \
+                                           tar bc gcc g++ ca-certificates
   Reading package lists... Done
   Building dependency tree
   Reading state information... Done
@@ -208,7 +209,8 @@ Now we can start the build::
   root@39d693b2a75d:/sage# ./configure
   checking for a BSD-compatible install... /usr/bin/install -c
   checking for root user... yes
-  configure: error: You cannot build Sage as root, switch to an unprivileged user.  (If building in a container, use --enable-build-as-root.)
+  configure: error: You cannot build Sage as root, switch to an unprivileged user.
+  (If building in a container, use --enable-build-as-root.)
 
 Let's just follow this helpful hint::
 
@@ -225,14 +227,16 @@ Using Sage's database of equivalent distribution packages
 At the end of the ``./configure`` run, Sage issued a message like the
 following::
 
-  configure: notice: the following SPKGs did not find equivalent system packages: arb boost_cropped bzip2 ... zeromq zlib
+  configure: notice: the following SPKGs did not find equivalent system packages:
+                     arb boost_cropped bzip2 ... zeromq zlib
   checking for the package system in use... debian
-  configure: hint: installing the following system packages is recommended and may avoid building some of the above SPKGs from source:
+  configure: hint: installing the following system packages is recommended and
+                   may avoid building some of the above SPKGs from source:
   configure:   $ sudo apt-get install libflint-arb-dev ... libzmq3-dev libz-dev
   configure: After installation, re-run configure using:
   configure:   $ ./config.status --recheck && ./config.status
 
-This information comes from Sage's database of equivalent distribution
+This information comes from Sage's database of equivalent system
 packages.  For example::
 
   root@39d693b2a75d:/sage# ls build/pkgs/arb/distros/
@@ -268,9 +272,9 @@ corresponding to its current state::
 
   root@39d693b2a75d:/sage# ^D
   [mkoeppe@sage worktree-ubuntu-latest]$ docker ps -a | head -n3
-  CONTAINER ID        IMAGE                   COMMAND                   CREATED             STATUS
-  39d693b2a75d        ubuntu:latest           "/bin/bash"               8 minutes ago       Exited (0) 6 seconds ago
-  9f3398da43c2        ubuntu:latest           "/bin/bash"               8 minutes ago       Exited (0) 8 minutes ago
+  CONTAINER ID   IMAGE           COMMAND       CREATED         STATUS
+  39d693b2a75d   ubuntu:latest   "/bin/bash"   8 minutes ago   Exited (0) 6 seconds ago
+  9f3398da43c2   ubuntu:latest   "/bin/bash"   8 minutes ago   Exited (0) 8 minutes ago
   [mkoeppe@sage worktree-ubuntu-latest]$ docker commit 39d693b2a75d ubuntu-latest-minimal-17
   sha256:4151c5ca4476660f6181cdb13923da8fe44082222b984c377fb4fd6cc05415c1
 
@@ -506,7 +510,8 @@ might not work on all platforms, ``surf``, which was marked as
   ...
   Makefile:31: recipe for target 'surf' failed
   make: *** [surf] Error 1
-  The command '/bin/sh -c make SAGE_SPKG="sage-spkg -y -o" ${USE_MAKEFLAGS} ${TARGETS_PRE}' returned a non-zero code: 2
+  The command '/bin/sh -c make SAGE_SPKG="sage-spkg -y -o" ${USE_MAKEFLAGS} ${TARGETS_PRE}'
+  returned a non-zero code: 2
 
 Note that no image id is shown at the end; the build failed, and no
 image is created.  However, the container in which the last step of
@@ -688,11 +693,11 @@ the one just after running the ``configure`` script (``configured``)::
 
 Let's verify that the images are available::
 
-  (base) egret:~/s/sage/sage-rebasing/worktree-algebraic-2018-spring (mkoeppe *$%>)$ docker images | head
-  REPOSITORY                                                TAG                               IMAGE ID
-  sage-centos-8-standard-with-targets                9.1.beta9-435-g861ba33bbc-dirty   7ecfa86fceab
-  sage-centos-8-standard-configured                  9.1.beta9-435-g861ba33bbc-dirty   4314929e2b4c
-  sage-centos-8-standard-with-system-packages        9.1.beta9-435-g861ba33bbc-dirty   4bb14c3d5646
+  [mkoeppe@sage sage]$ docker images | head
+  REPOSITORY                                    TAG                               IMAGE ID
+  sage-centos-8-standard-with-targets           9.1.beta9-435-g861ba33bbc-dirty   7ecfa86fceab
+  sage-centos-8-standard-configured             9.1.beta9-435-g861ba33bbc-dirty   4314929e2b4c
+  sage-centos-8-standard-with-system-packages   9.1.beta9-435-g861ba33bbc-dirty   4bb14c3d5646
   ...