cat print and join files
cat (short for concatenate) writes one or more files to standard output, one after another. It is the usual way to start a pipeline from a file, and the simplest way to glue files together.
Availability Preinstalled on macOS, Linux and BSD
Syntax
cat [options] [file ...]Common options
| Option | What it does |
|---|---|
-n | Number every output line |
-b | Number only non-blank lines |
-s | Squeeze runs of blank lines into one |
-A | Show tabs, line ends and other invisible characters (GNU). On macOS use -vet |
Examples
Show a file
cat notes.txtJoin files into a new one
cat january.jsonl february.jsonl > q1.jsonlNumber lines
cat -n script.shUse cat with sqx
Start a query from a file
Whatever cat prints becomes the stdin table.
cat users.csv | sqx "SELECT name, plan FROM stdin LIMIT 5"Query many JSON Lines files as one table
JSON Lines files can be joined with cat safely, because every line is a complete record.
cat logs/*.jsonl | sqx "SELECT type, COUNT(*) FROM stdin GROUP BY type"To combine CSV files that each have a header row, see tail -n +2 on the tail page, or load each file with sqx -f.
Full documentation
This page covers the essentials. For every option, see the official documentation:
Or read the manual in your terminal: man cat