Command Line Part 1

Lecture 01 Commands Line introduction

Let's find all HTML files:

$ find . -name "*.html"

Extended Eg

Let's ensure that all our html files use HTML5

$ find . -name "*.html" -exec grep -i 'doctype' {} \;

Commands

ls

• The command ls lists the files in a directory.
• The command is documented in the manual

$ man ls

(Hint: type q to quit the manual).

Options

Most commands take options. For example:

• -a, --all do not ignore entries starting with .
• -1 list one file per line. Avoid '' with -q or -b

So we may

$ ls -a -1
$ ls -a1
$ ls --all -1

Piping

Piping using the | allows combining commands.

$ rpm -qa

lists all the installed packages on a RedHat/Fedora system.

$ rpm -qa | grep -i "Acrobat"

searches the list to see if the Acrobat PDF reader is installed.

 Note: the try with acrobat doesnt work because I do not have install any PDF since I'm just using an emulator (Virtual Machine) and I have not install anything on it.

Complex Eg

How do you list all the software licences of packages installed on your system?

$ rpm -qa --qf "%{license}\n" | sort | uniq

Filesystem

Try

$ cd ~
$ ls
$ ls -a
$ cd Documents

What does the -a option for ls do?

 -a includes the files, since ls only include carpets

Conclusion

• There are many Linux commands.
• Each command has options.
• Some commands take other parameters.
• Commands can be combined quickly to give impressive functionality.
• The filesystem makes more sense than the Windows structure!