CODEWITHSUNDEEP
bashpostgresqlpsql
Homunculus Reticulli
Homunculus Reticulli

Reputation: 68486

Shell script to execute pgsql commands in files

I am trying to automate a set of procedures that create TEMPLATE databases.

I have a set of files (file1, file2, ... fileN), each of which contains a set of pgsql commands required for creating a TEMPLATE database.

The contents of the file (createdbtemplate1.sql) looks roughly like this:

CREATE DATABASE mytemplate1 WITH ENCODING 'UTF8';

\c mytemplate1

CREATE TABLE first_table ( 
 --- fields here ..
);

-- Add C language extension + functions
\i db_funcs.sql

I want to be able to write a shell script that will execute the commands in the file, so that I can write a script like this:

# run commands to create TEMPLATE db mytemplate1
# ./groksqlcommands.sh createdbtemplate1.sql

for dbname in foo foofoo foobar barbar
do
    # Need to simply create a database based on an existing template in this script
    psql CREATE DATABASE $dbname TEMPLATE mytemplate1
done

Any suggestions on how to do this? (As you may have guessed, I'm a shell scripting newbie.)

Edit

To clarify the question further, I want to know:

  1. How to write groksqlcommands.sh (a bash script that will run a set of pgsql cmds from file)
  2. How to create a database based on an existing template at the command line

Upvotes: 50

Views: 127486

Answers (5)

Erwin Brandstetter
Erwin Brandstetter

Reputation: 659297

First off, do not mix psql meta-commands and SQL commands. These are separate sets of commands. There are tricks to combine those (using the psql meta-commands \o and \\ and piping strings to psql in the shell), but that gets confusing quickly.

  • Make your files contain only SQL commands.
  • Do not include the CREATE DATABASE statement in the SQL files. Create the db separately, you have multiple files you want to execute in the same template db.

Assuming you are operating as OS user postgres and use the DB role postgres as (default) Postgres superuser, all databases are in the same DB cluster on the default port 5432 and the role postgres has password-less access due to an IDENT setting in pg_hba.conf - a default setup.

psql postgres -c "CREATE DATABASE mytemplate1 WITH ENCODING 'UTF8'
                  TEMPLATE template0"

I based the new template database on the default system template database template0. Basics in the manual here.

Your questions

How to (...) run a set of pgsql cmds from file

Try:

psql mytemplate1 -f file

Example script file for batch of files in a directory:

#! /bin/sh

for file in /path/to/files/*; do
    psql mytemplate1 -f "$file"
done

The command option -f makes psql execute SQL commands in a file.

How to create a database based on an existing template at the command line

psql -c 'CREATE DATABASE my_db TEMPLATE mytemplate1'

The command option -c makes psql execute a single SQL command string. Can be multiple commands, terminated by ; - will be executed in one transaction and only the result of the last command returned.
Read about psql command options in the manual.

If you don't provide a database to connect to, psql will connect to the default maintenance database named "postgres". In the second answer it is irrelevant which database we connect to.

Upvotes: 68

Joseph H
Joseph H

Reputation: 43

For that use case where you have to do it....

Here is a script I've used for importing JSON into PostgreSQL (WSL Ubuntu), which basically requires that you mix psql meta commands and SQL in the same command line. Note use of the somewhat obscure script command, which allocates a pseudo-tty:

$ more update.sh
#!/bin/bash
wget <filename>.json
echo '\set content `cat $(ls -t <redacted>.json.* | head -1)` \\ delete from <rable>; insert into <table> values(:'"'content'); refresh materialized view <view>; " | PGPASSWORD=<passwd> psql -h <host> -U <user> -d <database>
$

Upvotes: 1

Yordan Georgiev
Yordan Georgiev

Reputation: 5460

Store your sql scripts under a root dir Use dev,tst,prd parametrized dbs Use find to run all your pgsql scripts as shown here Exit on errors

Or just git clone the whole tool from here

Upvotes: 1

Spencer Rathbun
Spencer Rathbun

Reputation: 14910

If you're willing to go the extra mile, you'll probably have more success with sqlalchemy. It'll allow you to build scripts with python instead of bash, which is easier and has better control.

As requested in the comments: https://github.com/srathbun/sqlCmd

Upvotes: 1

Elias Dorneles
Elias Dorneles

Reputation: 23916

you can echo your commands to the psql input:

for dbname in foo foofoo foobar barbar
do
    echo """
CREATE DATABASE $dbname TEMPLATE mytemplate1
""" | psql
done

Upvotes: 4

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