Let’s have some fun with Linux® commands!  There’s lots of interesting and weird commands on most Linux® systems, so lets’ have some fun and try out some fun Linux® commands.

We start with one called figlet.  I know what you’re thinking, who names these things?  At least with Dr. Strange you know exactly what’ you’re getting, you’re getting a strange doctor.  figlet just sounds weird.

Image from clipartfest.com

Let’s see what we get when we try it:

Alpha:~ computerlamp$ figlet test
  m                    m
 mm#mm   mmm    mmm   mm#mm
   #    #"  #  #   "    #
   #    #""""   """m    #
   "mm  "#mm"  "mmm"    "mm

Well isn’t that neat?  It took our word and turned into a banner made of characters.  Now I’m not saying this isn’t a useful command at some point, because clearly someone made it.  I’m saying it is a rather silly command.  It’s also one of many fun Linux® commands!

There isn’t a man page for figlet, but if you look at the output of figlet -h you’ll see all sorts of flags you can use with it.

Let’s do one more.

Alpha:~ computerlamp$ figlet Hi There

 m    m   "          mmmmmmm #
 #    # mmm             #    # mm    mmm    m mm   mmm
 #mmmm#   #             #    #"  #  #"  #   #"  " #"  #
 #    #   #             #    #   #  #""""   #     #""""
 #    # mm#mm           #    #   #  "#mm"   #     "#mm"

That was fun!

There’s another way to do it, of course.  That’s called banner and it’s another of the fun Linux® commands.  It makes similar messages, but they look a little different:

Alpha:~ computerlamp$ banner -w 40
Message: Hi There
          #                         #
          #                         #
          ###########################
          ###########################
          #              #          #
          #              #          #
                         #
                         #
                         #
          #              #          #
          ###########################
          ###########################
          ###########################
          #                         #

          #              #
          ################    ####
          ################    ####
          ################     ##











                                #####
                                #####
                                   ##
                                    #
          #                         #
          #                         #
          ###########################
          ###########################
          #                         #
          #                         #
                                    #
                                   ##
                                #####
                                #####
          #                         #
          ###########################
          ###########################
          ###########################
                        #
                        ##
                        ##
          ################
          ###############
          ############
               #####
            ###########
           ##############
          ##     #     ##
          #      #       #
          #      #       #
          #      #      ##
           #     ########
            ##   ######
                 ###
          #              #
          ################
          ################
          ################
                      ##
                       ##
                     #####
                    ######
                    #####

               #####
            ###########
           ##############
          ##     #     ##
          #      #       #
          #      #       #
          #      #      ##
           #     ########
            ##   ######
                 ###

When I ran the banner command, I gave it that -w flag so that it wouldn’t fill the entire string.  Try it without any flag and see what you get.  If you don’t pass in the string for the message, it asks you what you want to use.

There’s more than one way to do it!  I think that should be one of the mottos of Linux®.  There’s always more than one way to do it.  That’s what we’re going to talk about in this post, some of the more than one way to do the commands we’ve already learned.

We learned about ls and how it has flags.  One of the most useful flags is -l which lets us see all the group ownerships and users and everything we could need.

For example:

Alpha:~ computerlamp$ ls -l
total 164
drwxr-xr-x   3 root root 69632 Aug  9 13:15 bin
drwxr-xr-x   2 root root  4096 Jan  5  2016 games
drwxr-xr-x  82 root root 20480 Jul 17 16:18 include
drwxr-xr-x 111 root root 24576 Jul 17 16:18 lib
drwxr-xr-x   3 root root 12288 Aug  3 06:43 libexec
drwxr-xr-x  19 root root  4096 Dec 27  2016 local
drwxr-xr-x   2 root root 12288 Jul 28 18:58 sbin
drwxr-xr-x 199 root root  4096 Jul 28 18:58 share
drwxr-xr-x   2 root root  4096 Apr 19  2012 src
drwxr-x---   3 root root  4096 Jan  5  2016 var

I listed all the files and directories in /usr using ls -l.  I can do the same thing with the command vdir.

Alpha:~ computerlamp$ vdir /usr
total 164
drwxr-xr-x   3 root root 69632 Aug  9 13:15 bin
drwxr-xr-x   2 root root  4096 Jan  5  2016 games
drwxr-xr-x  82 root root 20480 Jul 17 16:18 include
drwxr-xr-x 111 root root 24576 Jul 17 16:18 lib
drwxr-xr-x   3 root root 12288 Aug  3 06:43 libexec
drwxr-xr-x  19 root root  4096 Dec 27  2016 local
drwxr-xr-x   2 root root 12288 Jul 28 18:58 sbin
drwxr-xr-x 199 root root  4096 Jul 28 18:58 share
drwxr-xr-x   2 root root  4096 Apr 19  2012 src
drwxr-x---   3 root root  4096 Jan  5  2016 var

There’s more than one way to list the files.  I can even do it with find though it’s much more work than just doing vdir or ls.

If I leave off the -l flag, I get:

Alpha:~ computerlamp$ ls /usr
bin  games  include  lib  libexec  local  sbin	share  src  var

I get the same output if I do the following two commands, just with fewer spaces:

Alpha:~ computerlamp$ cd /usr
Alpha:~ computerlamp$ echo *

In other words, there’s more than one way to do it.  I can ls -l or vdir, or I can ls or use the echo * trick.

This is certainly not the only case of more than one command to do the same thing.  It keeps things interesting when you’re learning Linux®.

I bet your cell phone knows what today’s date is.  Your computer should know too, right?  Depending on how your system is set up, you might even see the current date on your screen.  Well, your command line also knows what date it is and can tell you if you ask it.  The command is called (drum roll here please):  date

Alpha:~ computerlamp$ date
Fri Apr 28 15:21:15 EDT 2017

That’s the date that I wrote this and it even include the actual time.  That’s rather useful, isn’t it?

What else can we do?  Well, let’s find out what today’s month looks like.  I had an appointment on the 15th but I forgot what day of the week that was.  Well, there’s a command for that!

Alpha:~ computerlamp$ cal
     April 2017
Su Mo Tu We Th Fr Sa
                   1
 2  3  4  5  6  7  8
 9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25 26 27 28 29
30

That’s one useful command, isn’t it?  I can see that the 15th was on a Saturday.  But hey, it’s almost the end of the month, I want to know what day of the week May 14th is.  Well, I can ask that too:

Alpha:~ computerlamp$ cal 5 2017
      May 2017
Su Mo Tu We Th Fr Sa
    1  2  3  4  5  6
 7  8  9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30 31

I just asked it for the calendar for the fifth month of the year 2017.  Huh.  I wonder what happens if I ask it for the calendar for May 2020.

Alpha:~ computerlamp$ cal 5 2020
      May 2020
Su Mo Tu We Th Fr Sa
                1  2
 3  4  5  6  7  8  9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31

What do you know, that works too!  I can ask for the month and year for almost any time!  I bet that would come in use when Flash starts playing with the timeline again

The Flash Changing Time Again!

I bet if he goes way back into the past I can figure out what the calendar looks like.

According to this Captain America disappeared around April 18, 1945.  That was a Wednesday!

Alpha:~ computerlamp$ cal April 1945
     April 1945
Su Mo Tu We Th Fr Sa
 1  2  3  4  5  6  7
 8  9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28
29 30

So The Flash could go back in time and rescue him, right?  Except that Captain America is Marvel and The Flash is DC.  Oh well, details, right?

So one day, Tony Stark noticed a wasp in his lab.  He could put on the whole suit to kill it, or he could just put on the glove.  The whole suit is overkill, right?  Just one glove would take care of the whole thing.  There’s a similar idea in Linux®.  Using su to get root powers is overkill, the ‘just enough’ command is sudo.

Iron Man’s Glove vs Wasp

sudo lets you execute a command as another user.  You can be root, you can be tonystark, batman, spock… you can be anyone you want, but you have to be given the power.  You can’t just walk up to the computer terminal and say ‘today, I’ll be batman, Batman’s user name.  I’ll do whatever batman can do on this Linux® system because sudo will let me’.

That’s kind of like putting on Batman’s suit and declaring yourself Batman.  It doesn’t work like that… though I wouldn’t mind being Batman for a day and driving around in the Batmobile.  That thing looks awesome.

Once you’re given permissions, you execute the commands like this:

Alpha:~ computerlamp$ sudo -u batman vi plans

If I have the permissions to do it, I can edit the plans file as batman.  I’m hoping it contains the plans for how to stop the Riddler.  Riddles aren’t my thing.

Anyway, how do you know what commands you have?  Well, there’s a flag for that!  (The other Linux® motto.)

Alpha:~ computerlamp$ sudo -l
Matching Defaults entries for computerlamp on Alpha:
    env_reset, env_keep+=BLOCKSIZE, env_keep+="COLORFGBG COLORTERM",
    env_keep+=__CF_USER_TEXT_ENCODING, env_keep+="CHARSET LANG LANGUAGE LC_ALL LC_COLLATE
    LC_CTYPE", env_keep+="LC_MESSAGES LC_MONETARY LC_NUMERIC LC_TIME", env_keep+="LINES
    COLUMNS", env_keep+=LSCOLORS, env_keep+=SSH_AUTH_SOCK, env_keep+=TZ, env_keep+="DISPLAY
    XAUTHORIZATION XAUTHORITY", env_keep+="EDITOR VISUAL", env_keep+="HOME MAIL",
    lecture_file=/etc/sudo_lecture

User computerlamp may run the following commands on Alpha:
    (ALL) ALL

So the first part of that response we’ll talk about another time.  It’s the last line that’s the most interesting.  It says that I can run all commands on Alpha.  Every single one!

So why do I use sudo rather than su?  Well, it’s to keep myself from making mistakes. If I have to think about each command before I use it, then I’ll be more careful.

Remember, for both sudo and su, it’s like Spiderman’s Uncle Ben said.

Spiderman!

With great power comes great responsibility!

Before we go back into the world of Linux (having spent time in the world of networking), let’s talk about users again.  In particular, the SuperUser also known as Root.  Root is his every day name, SuperUser is his power!  And with great power comes great responsibility.

Groot not Root

That’s Groot, not root, even though they rhyme.  Groot is a superhero, root is a superuser, and root doesn’t go around saying ‘I am Groot’ all the time.  They’re both super though.

SuperUsers’s great power is that he can do anything on a system and  I do mean, anything.  You change the permissions on your file so that you’re the only one that can see it?  Well, the superuser can see it too. He’s all powerful like Superman, but without that annoying green rock allergy.

His username is root and because he’s so powerful, he shouldn’t be logged in unless he’s absolutely needed.  The administrator of your system shouldn’t keep him logged in, but there’s a command to see who is logged in.  It’s called who.

Alpha:~ computerlamp$ who
computerlamp  console  Mar 17 08:01

There I am, logged into the system and I don’t have root logged into my system right now and that’s a good thing.

Since root is a user, he (or she!) has a password.  If you know the password, you can become root.  Like IronMan putting on his suit or BatMan suiting up, you can put on the root armor and be… SuperUser!  And like I always say, there’s a command for that.  This one is called su.

Alpha:~ computerlamp$ su
Password:
Alpha:~ :~ root#

You have to know the password in order for it to work.  If you don’t know the password, don’t try to do this.  It means you don’t have the permission to do it and if you try, you’re attempting to go around the system’s security and that’s a bad thing.  It’s like trying to lift Thor’s hammer and you’re not worthy.

If your root password gets out, then that’s a security problem.  When we made the shield group to hide the helicarrier plans, we thought we were safe from prying eyes.  But if Hydra got the root password, it wouldn’t matter.  That’s why it’s so important to keep that root password safe. The administrator of the system shouldn’t share it with anyone who doesn’t absolutely need it.