CentOS 6.4
Here’s a few very quick and basic commands to do things with files via the terminal. These can be vastly improved upon; please comment if you have better methods for this.
Basic commands
1 2 3 4 5 6 | // view the first 25 lines in a file $ head -25 filename.sql // view the last 25 lines in a file $ tail -25 filename.sql // delete the first 25 lines using sed $ sed -i '1,25d' filename.sql |
Heads and Tails, get it? 😉 Clever, these ‘nix folks! These could also be complicated as follows (this becomes useful when we begin chaining commands together with the pipe | connector).
1 2 3 4 | // view the first 25 lines in a file $ cat filename.sql | head -25 // view the last 25 lines in a file $ cat filename.sql | tail -25 |
Let’s copy sections of a HUGE file into a smaller file.
Add Complexity With Pipes
1 2 3 4 | // create empty file new.sql and insert the first 25 lines of filename.sql into it $ cat filename.sql | head -25 > new.sql // append first 25 lines of filename.sql to existing data in new.sql $ cat filename.sql | head -25 >> new.sql |
1 2 3 4 | // replace 'old' with 'new' in a file $ sed 's/old/new/g' filename.sql // string some commands together $ cat filename.sql | head -25 | sed 's/old/new/g' > new.sql |
This is just a quick brain-dump.