slash command is a psql meta-command (also known as "backslash command"), beginning - as the name implies - with a backslash ("
Slash commands perform a variety of functions, including executing queries and specifying the result output format, setting psql options and even forming the basis for a simple scripting language.
A summary of available slash commands in psql can be retrieved by entering
postgres=# SELECT 1\g ?column? ---------- 1 (1 row)
For useful tips on working with slash commands, see the following psql hacks: