A really simple, but useful, UNIX command is head, which will display the first 5 lines in a text file, great for quickly checking outputs. You can also use the n flag to specify the number of line.
# View first 5 lines head bigtextfile.csv # View first 10 lines head -n 10 bigtextfile.csv
There is also a coresponding tail command to view the last lines.
# View first 5 lines tail bigtextfile.csv # View first 10 lines tail -n 10 bigtextfile.csv