cat -> catenate, Concatenate
$ cat dictionary.txt
rm -> remove
$ rm SillyFile.txt
$ rm -i ValuableFile.txt
$ rm -i google.html rm: remove regular file 'google.html'? y
$ rmdir hogehoge
$ grep shell dictionary.txt
bombshell
bombshell’s
bombshells
bushelled
bushelling
cockleshell
cockleshell’s
cockleshells
eggshell
eggshell’s
eggshells
nutshell
nutshell’s
nutshells
seashell
seashell’s
seashells
shell
shell’s
shellac
shellac’s
shellacked
shellacking
shellacs
shelled
sheller
shellfish
shellfish’s
shellfishes
shelling
shells
tortoiseshell
tortoiseshell’s
tortoiseshells
