cat concatenates files

$ cat myfile.txt prints contents of myfile.txt|

$ cat *.txt prints all .txt files put together!

you can use cat as an EXTREMELY BASIC text editor:

1. Run $ cat > file.txt
2. type the contents (don’t make mistakes (smiley face))
3. press ctrl+d to finish

cat -n

prints out the file with line numbers!

1. Once upon a midnight..
2. Over many a quaint.
3. While I nodded, nearly

zcat

cats a gzipped file!

Actually just a 1-line shell script that runs gzip -cd, but easier to remember.

tee

tee file.txt will write. its stdin to both stdout and file.txt

stdin > tee a.txt > stdout and a.txt

how to redirect to a file owned by root

$ sudo echo "hi">> x.txt

this will open x.txt as your user, not as root, so it fails!

$ echo "hi" I sudo tee -a x.txt will open x.txt as root (smiley face)