# random hex-calculation to let your terminal look busy
cat /dev/urandom | hexdump -C | grep "ca fe"
#cat is used to read text files.
# cat concatenates a list of files
cat file1 file2
# abusing cat to read a single file is considered bad practice
cat onefile | foo # DON'T DO THIS
# instead use the following
< onefile foo
# Show tabs in a file
cat -T file.txt
# merge two files keeping only unique lines
cat file1 file2 | sort | uniq >> file3