Ciro Santilli @cirosantilli 37

 Articles (11k) Discussions (24) Comments (52) Follows  Received likes

 New  Updated  Top  Announced  A-Z  Liked  Followed

PostgreSQL getting started  Updated 2025-05-21  +Created 1970-01-01

On Ubuntu 20.10 PostgreSQL 12.6, login with psql on my default username without sudo fails with: stackoverflow.com/questions/11919391/postgresql-error-fatal-role-username-does-not-exist

This is the one that worked on Ubuntu 21.04: stackoverflow.com/questions/11919391/postgresql-error-fatal-role-username-does-not-exist/38444152#38444152

sudo -u postgres createuser -s $(whoami)
createdb $(whoami)

Explanation:

sudo -u postgres uses the postgres user via peer authentication
-s in createuser -s: make it a superuser
createdb: TODO why do we have to create a table with the same name as the user? Otherwise login fails.

You can now run psql without any password. This works without password due to peer authentication:

sudo cat /etc/postgresql/12/main/pg_hba.conf

shows that peer authentication is available to all users apparently:

local   all             postgres                                peer

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     peer

List users:

psql -c '\du'

output:

                                    List of roles
  Role name  |                         Attributes                         | Member of
-------------+------------------------------------------------------------+-----------
 ciro        | Superuser, Create role, Create DB                          | {}
 owning_user |                                                            | {}
 postgres    | Superuser, Create role, Create DB, Replication, Bypass RLS | {}

Delete user later on:

psql -c 'DROP USER username;'

Create a database:

createdb testdb0

Help toplevel:

help

Get help for Postgres commands such as \h and so on:

\?

List supported SQL commands:

\h

Show syntax for one type of command:

\h SELECT

List all databases:

psql -c '\l'

which shows:

    Name     |  Owner   | Encoding |   Collate   |    Ctype    |   Access privileges
-------------+----------+----------+-------------+-------------+-----------------------
 ciro        | postgres | UTF8     | en_GB.UTF-8 | en_GB.UTF-8 |
 postgres    | postgres | UTF8     | en_GB.UTF-8 | en_GB.UTF-8 |
 template0   | postgres | UTF8     | en_GB.UTF-8 | en_GB.UTF-8 | =c/postgres          +
             |          |          |             |             | postgres=CTc/postgres
 template1   | postgres | UTF8     | en_GB.UTF-8 | en_GB.UTF-8 | =c/postgres          +
             |          |          |             |             | postgres=CTc/postgres
 testdb0     | postgres | UTF8     | en_GB.UTF-8 | en_GB.UTF-8 |
(6 rows)

Delete a database:

psql -c 'DROP DATABASE "testdb0";'

If you didn't give a database from the command line e.g.:

psql

you can do that afterwards with:

\c testdb0

Let's create a table and test that it is working:

psql testdb0 -c 'CREATE TABLE table0 (int0 INT, char0 CHAR(16));'

List tables, no special tables:

psql testdb0 -c '\dt'

gives:

        List of relations
 Schema |  Name  | Type  | Owner
--------+--------+-------+-------
 public | table0 | table | ciro
(1 row)

View table schema: stackoverflow.com/questions/109325/postgresql-describe-table

psql testdb0 -c '\d+ table0'

output:

                                      Table "public.table0"
 Column |     Type      | Collation | Nullable | Default | Storage  | Stats target | Description
--------+---------------+-----------+----------+---------+----------+--------------+-------------
 int0   | integer       |           |          |         | plain    |              |
 char0  | character(16) |           |          |         | extended |              |

Insert some data into it and get the data out:

psql testdb0 -c "INSERT INTO table0 (int0, char0) VALUES (2, 'two'), (3, 'three'), (5, 'five'), (7, 'seven');"
psql testdb0 -c 'SELECT * FROM table0;'

output:

 int0 |      char0
------+------------------
    2 | two
    3 | three
    5 | five
    7 | seven
(4 rows)

Delete the table:

psql testdb0 -c 'DROP TABLE table0;'

 Read the full article

Website stack  Updated 2025-05-21  +Created 1970-01-01

 Read the full article

bsub get job stdout and stderr  Updated 2025-05-21  +Created 1970-01-01

 View more

By default, LSF only sends you an email with the stdout and stderr included in it, and does not show or store anything locally.

One option to store things locally is to use:

bsub -oo stdout.log -eo stderr.log 'echo myout; echo myerr 1>&2'

as documented at:

Or to use files with the job id in them:

bsub -oo %J.out -eo %J.err 'echo myout; echo myerr 1>&2'

By default bsub -oo:

also contains the LSF metadata in addition to the actual submitted process stdout
prevents the completion email from being sent

To get just the stdout to the file, use bsub -N -oo which:

stores only stdout on the file
re-enables the completion email

as mentioned at:

Another option is to run with the bsub -I option:

bsub -I 'echo a;sleep 1;echo b;sleep 1;echo c'

This immediately prints stdout and stderr to the terminal.

 Read the full article

Cytoplasm  Updated 2025-05-21  +Created 1970-01-01

 Read the full article

German physics journal  Updated 2025-05-21  +Created 1970-01-01

 Read the full article

Lab vs cyclotron X-ray crystallography  Updated 2025-05-21  +Created 1970-01-01

 View more

cyclotrons produce the better images, but they are expensive/you have to move to them and order a timeslot.

Lab-based just use some X-ray source from the lab, so it is much move convenient e.g. for a pharmaceutical company doing a bunch of images. The Wikipedia image shows such a self-contained lab system: en.wikipedia.org/wiki/File:Freezed_XRD.jpg

 Read the full article

MediaWiki  Updated 2025-05-21  +Created 1970-01-01

 View more

Open source software engine created for and used by Wikipedia.

 Read the full article

Visual math HTML book  Updated 2025-05-21  +Created 1970-01-01

 View more

When you see some tagged examples, you will immediately know what this means.

 Read the full article

btcdeb  Updated 2025-05-21  +Created 1970-01-01

 View more

github.com/bitcoin-core/btcdeb

Tested on Ubuntu 23.10:

sudo apt install libtool
git clone https://github.com/bitcoin-core/btcdeb
cd btcdeb
git checkout 4fd007e57b79cba9b5ffdf5ffe599778c0d63b88
./autogen.sh
./configure
make -j

Patch submited at: github.com/bitcoin-core/btcdeb/pull/143

Then we use it;

./btcdeb '[OP_1 OP_2 OP_ADD]'

and inside the shell:

btcdeb 5.0.24 -- type `./btcdeb -h` for start up options
LOG: signing segwit taproot
notice: btcdeb has gotten quieter; use --verbose if necessary (this message is temporary)
3 op script loaded. type `help` for usage information
script  |  stack 
--------+--------
1       | 
2       | 
OP_ADD  | 
#0000 1
btcdeb> step
                <> PUSH stack 01
script  |  stack 
--------+--------
2       |      01
OP_ADD  | 
#0001 2
btcdeb> step
                <> PUSH stack 02
script  |  stack 
--------+--------
OP_ADD  |      02
        |      01
#0002 OP_ADD
btcdeb> step
                <> POP  stack
                <> POP  stack
                <> PUSH stack 03
script  |  stack 
--------+--------
        |      03
btcdeb> step
script  |  stack 
--------+--------
        |      03
btcdeb> step
at end of script
btcdeb>

 Read the full article