In linux all commands and programs have 3 main I/O interfaces:
Standard Out (>, 1>)
Standard In (<)
Standard Error (2>)

mkdir scratch
cd scratch
cp ~egdaniel/teaching/cs108/files/artists.txt .
man cat
cat artists.txt
cat
cat > file.txt
cat < artists.txt
cat artists.txt file.txt > combo.text
cat *.txt > combo2.text
cp artists.txt artists2.txt
cat file.txt >> artists2.txt
cat file.txt notafile.txt > test.txt
cat test.txt
cat file.txt notafile.txt 2> error.txt
cat notafile.txt file.txt 2> error.txt
cat file.txt notafile.txt 1> out.txt 2> error2.txt
cat file.txt notafile.txt &> both.txt
cat notafile.txt file.txt &> both.txt
man tr
tr abc ABC
cat artists.txt | tr abc #@$
cat artists.txt | tr abc '#@$'
cat artists.txt | tr abc '&'
cat artists.txt | tr abc '#@'
cat artists.txt notafile.txt > afile | cat
history
history | grep 'mkdir'
history | grep 'mkdir' > somefile.txt
cat somefile.txt