ubuntu practical guide
The shell doesn't require that the name of the program appear first on the command line ubuntu@ubuntu:~/test1$ ls ubuntu@ubuntu:~/test1$ <b cat ubuntu tty7 2015-03-15 02:28 (:0) ubuntu pts/0 2015-03-15 02:33 (:0) Sun Mar 22 10:20:41 PDT 2015 ubuntu@ubuntu:~/test1$ >t <b cat ubuntu@ubuntu:~/test1$ ls b t ----------------------- The shell doesn't look through all directories but only the ones specified by the variable named PATH ----------------------- ubuntu@ubuntu:~/test1$ cat b ubuntu tty7 2015-03-15 02:28 (:0) ubuntu pts/0 2015-03-15 02:33 (:0) Sun Mar 22 10:20:41 PDT 2015 ubuntu@ubuntu:~/test1$ cat b | grep -o ubuntu | tr ubuntu UBUNTU UBUNTU UBUNTU ubuntu@ubuntu:~/test1$ ---------------------- ubuntu@ubuntu:~/test1$ who | tee who.out | grep ubuntu ubuntu tty7 ...