Unix, and of course Linux, users learn to quickly get familiar with the daily-use cat utility. At first glance, all cat does is spit out the contents of a file to the terminal.
For example, say we have two plain text files, myfile1.txt and myfile2.txt:
$ cat myfile1.txtHello,Linux System Programming,World.$ cat myfile2.txtOkey dokey,bye now.$
Okay. Now check this out:
$ cat myfile1.txt myfile2.txtHello,Linux System Programming,World.Okey dokey,bye now.$
Instead of needing to run cat twice, we ran it just once, by passing the two filenames to it as parameters.
In theory, one can pass any number of parameters to cat: it will use them all, one by one!
Not just that, one can use shell wildcards too (* and ?; in reality, the shell will first ...
