Using psql without entering password

Sometimes, we need to run psql command without entering the password, even though the account is protected with password. The usual situations are, when we are running the psql command in a script, or we have to constantly monitor the output of psql commands using watch. Here is the method on how to achieve that.

Create a .pgpass file inside the user's home directory who's going to access psql without password

$ touch ~/.pgpass

Follow below format to add the user's details into pgpass

hostname:port:database:username:password

$ echo "10.10.10.10:5432:mydatabase:myuser:mysuperlongpassword" > ~/.pgpass

We can also use wildcard, such as *. If you password contains ":" or "\", use "\" to escape them

$ echo "*:*:mydatabase:myuser:mysuperlongpassword" > ~/.pgpass

Give a proper permission to the file, nobody accept the owner of the home directory is allowed to use the file

$ chmod 0600 ~/.pgpass

Now we should be able to use psql to mydatabase as myuser, without entering any password

$ psql -h localhost -U myuser mydatabase

postgres=# 

Checking if our password is based on a dictionary word on linux command line

There is a package in linux that can be used to check the our password, if it is based on a dictionary word, and that is libcrack (or libcrack2 in debian based).

To install the package:

• In redhat family:

# yum install cracklib -y

• In debian family:

# apt install libcrack2

To use, just run cat and pipe it against cracklib-check command, and supply your password after that. Do not forget to type ctrl-d or ctrl-c to get back to the shell, once done.

$ cat | cracklib-check

password 

password: it is based on a dictionary word

$ cat | cracklib-check

Xeir3oongex*

Xeir3oongex*: OK