Rewrite Readme-1

README.md

@@ -49,7 +49,7 @@ make patch
 6) Compile and install PostgreSQL:
 
 ```shell
-make install-postgres prefix=$PWD/pgsql  # or another prefix of your choice
+make install-postgres prefix=$PWD/pgsql  # or some other prefix of your choice
 ```
 
 7) Add the newly created binaries to the PATH:
@@ -209,18 +209,18 @@ sudo pip3 install testgres
 
 ### Testing
 
-Install PostgreSQL and ptrack as described in [Installation](#installation), install the testing prerequisites, then do:
+Install PostgreSQL and ptrack as described in [Installation](#installation), install the testing prerequisites, then do (assuming the current directory is `ptrack`):
 ```shell
-export PATH=/path/to/pgsql/bin:$PATH
 git clone https://github.com/postgrespro/pg_probackup.git ../pg_probackup  # clone the repository into postgres/contrib/pg_probackup
+# remember to export PATH=/path/to/pgsql/bin:$PATH
 make install-pg-probackup USE_PGXS=1 top_srcdir=../..
 make test-tap USE_PGXS=1
 make test-python
 ```
 
-If `pg_probackup` is cloned to a location other than `postgres/contrib/pg_probackup` specify the path to the `pg_probackup` directory when building `pg_probackup`:
+If `pg_probackup` is not located in `postgres/contrib` then additionally specify the path to the `pg_probackup` directory when building `pg_probackup`:
 ```shell
-make install-pg-probackup USE_PGXS=1 top_srcdir=../.. pg_probackup_dir=/path/to/pg_probackup
+make install-pg-probackup USE_PGXS=1 top_srcdir=/path/to/postgres pg_probackup_dir=/path/to/pg_probackup
 ```
 
 You can use a public Docker image which already has the necessary build environment (but not the testing prerequisites):
@@ -235,7 +235,8 @@ dev@a033797d2f73:~$
 | Variable  | Possible values | Required | Default value  | Description |
 | -         | -               | -        | -              | -           |
 | NPROC     | An integer greater than 0 | No | Output of `nproc` | The number of threads used for building and running tests |
-| PG_CONFIG | File path | No | pg_config | The path to the `pg_config` binary. Can be set to specify a custom location of `pg_config`. |
+| PG_CONFIG | File path | No | pg_config (from the PATH) | The path to the `pg_config` binary. A relative path starts at the current working directory. |
+| PG_PROBACKUP_DIR | File path | No | ../pg_probackup | The path to the `pg_probackup` directory. A relative path starts at the current working directory. |
 | TESTS     | A Pytest filter expression | No | Not set (run all Python tests) | A filter to include only selected tests into the run. See the Pytest `-k` option for more information. This variable is only applicable to `test-python` for the tests located in [tests](https://github.com/postgrespro/pg_probackup/tree/master/tests). |
 | TEST_MODE | normal, legacy, paranoia | No | normal | The "legacy" mode runs tests in an environment similar to a 32-bit Windows system. This mode is only applicable to `test-tap`. The "paranoia" mode compares the checksums of each block of the database catalog (PGDATA) contents before making a backup and after the restoration. This mode is only applicable to `test-python`.|