LinuxQuestions.org - cat command -s , -n

Well, as a general advice you should carefully read the man pages, especially when looking for options and their meaning. For example:

Code:

$ man cat

<scroll>

      -n, --number

              number all output lines



      -s, --squeeze-blank

              suppress repeated empty output lines

<omitted>

At this point some exercise is useful to test our understanding. For example I create a file with 4 lines (leaving two lines in the middle empty) using echo and redirection:

Code:

$ echo first line > file

$ echo >> file

$ echo >> file

$ echo fourth line >> file

Ok. Let's try with cat and its options:

Code:

$ cat file

first line





fourth line

The above is just the content of the file, as expected (a usage of cat - without options - is to print out the content of a file). Let's try our options:

Code:

$ cat -n file

    1  first line

    2

    3

    4  fourth line

$ cat -s file

first line



fourth line

Mirroring your question, what's the difference between -n and -s now? :jawa: