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Update metadata and transcripts through end of July 2026

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Episode: 4544
Title: Uncommon Commands, Episode 2
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr4544/hpr4544.mp3
Transcribed: 2026-07-31 16:13:38 (official HPR transcript)
---
This is Hacker Public Radio Episode 4544, for 2026-01-01
Today's show is entitled, "Uncommon Commands, Episode 2"
The host is Deltaray and the duration is 00:11:49
The flag is Clean, and the license is CC-BY-SA
The summary is "A summary of four commands, mtr, scrot, zless, and last"
Hello and welcome to Hacker Public Radio in Episode 2 of the Uncommon Command series.
The first command I want to mention in this episode is MTR.
You've probably used the pink command before to check to see if your network is working.
Back in the day I used to ping Yahoo.com all the time and it seemed like a lot of other
people like to use them too based on tutorials and presentations and documentation at
the time.
I suspect I picked up on the practice from some tutorial website somewhere or some colleague
back in the days of my early career.
I always wondered if Yahoo received so many ICMP Echo requests from around the internet
that they had to dedicate a person to deal with all that traffic.
Along the same lines as Ping, you may have also seen or used the Tracerout Command.
This is another network connectivity diagnostics program that has been around since the
early days of the internet.
It's fun to see the path that your packets take from your house or to get to various
websites and destinations around the globe.
One time someone even made a special Tracerout destination that listed out the opening
crawling text from Star Wars.
That host is long gone, but you can try running a Tracerout against another host called
bad dot horse for a similar experience.
After tracing to the destination it should cycle through a list of host that are the
lyrics to the song Bad Horse.
Just make sure that you give enough hops to get through the whole song.
Use the dash M option with it like this.
Tracerout space-M space 100 space bad dot horse.
To build on the functionality of Tracerout there's another program called MTR that isn't
as well known, but was created back in 1997 by Matt Kimball.
It originally stood for Matt's Tracerout.
In 1998 Roger Wolf took over the development, changed the meaning to my Tracerout, however
according to the GitHub repo Matt Kimball still involved with the development.
Instead of just being another Tracerout program, MTR combines the functionality of Tracerout
in ping with a real time display to create something new.
By using the EndCurse's library to draw on your terminal, MTR takes over your terminal
and instead of just a static printout it shows each leg of the journey and updates the
statistics to that leg and the host in real time.
This allows you to monitor over time and better pinpoint where the problem might be.
To start the program simply type MTR followed by the destination host name or IP address.
We can use Yahoo.com as our target.
If you're using Linux as your desktop and want to force MTR to run inside the terminal,
then use the dash T option for terminal or text, however you want to remember it.
So use the command MTR Space-T Space Yahoo.com.
It should open a Curse's Base 2E Interface or TUI Interface and start tracing through
the host to Yahoo.com.
One advantage you might notice depending on the path is that while Tracerout would stall
at any host that doesn't reply to an ICMP request, MTR will skip that host and come back
to it each cycle so you can see the complete path right away even if you don't get all
the routers to respond to you.
At each hop it will give you statistics to the router such as packet lost and round trip
ping time.
This can help you narrow down where a problem might be.
One thing to keep in mind through those that a lot of routers are set up to either ignore
ICMP requests like this or deprioratize them.
So packet loss at a router might not truly indicate the source of the problem.
It's more art than science, but it's definitely interesting and great for showing off.
Across the top you'll see a list of options.
One of which is display mode which you can cycle through the display modes by pressing
the letter D. This will give you a few different types of histograms which can show you
your connectivity metrics over time.
You can press the R key to reset the statistics and to quit MTR you can just press Q or Control
C.
The next command I'd like to talk about is Scroat or Scrot or however you want to pronounce it.
It's a screen capture utility for the command line.
It's spelled SCROT to use it from X Windows you simply run Scrot.
By default with no arguments it creates a screenshot of the whole screen and saves it to
a file according to the current date and time including seconds and the resolution of the
image captured.
It also saves as a PNG image type file by default for lossless capture of data.
But why take screenshots?
Well they are often useful for capturing a program you're having trouble with on your
system so that you can share it with tech support or some tech forum where you're trying to
show what you're seeing.
If you're helping a colleague friend or relative with their problem you might
ask them to take a screenshot so that you can see what they are seeing.
Or you might take a screenshot of your own to share it with them so you can show them what you're seeing.
Given the dynamic nature of computing it can also be useful to preserve history by
taking screenshots of web pages, applications, desktops and so on as they are prone to change
over time and they might not be possible layer to see the previous functionality or recreate it.
They also are more accepted as a form of proof although of course it's not that hard to
fake screenshots so your mileage may vary on trying to convince somebody.
It might also just be for nostalgic purposes so that you can go back later and remember
what your computing experience used to be like.
Scrot was originally written by Tom Gilbert and released on October 26th of the year 2000.
I first discovered it in 2012 when somebody recommended it to me so it's been around for a long time.
There are other screenshot programs out there as well but I find Scrot to be
nice minimal and scriptable through shell scripts of your own.
However, if you want more functionality you might look at a program called FlameShot,
spelled FL-A-M-E-S-H-O-T which allows command line control as well and has a nice compact on-screen
menu for quickly making changes and annotations that you're likely to make with a screenshot.
The next command is Zless.
Sooner or later you'll encounter a compressed file that you'd like to view or search in.
For me it's usually a rotated log file from a previous month that has been compressed.
But it's kind of a pain to have to decompress the file just to work with it and you might not even
have enough space when your storage to decompress it. This is where the command Zless comes in.
With a Zless you can view a file that has been compressed with GZIP.
Zless works by decompressing part of the file in memory. This way you don't create a new file in the
disk and don't modify the original file. You can do most of the things that less can do so it's very
handy when working with GZIP compressed files. But that's not the only command in the set of
commands. There's also Z-Grepp which allows you to prep transparently on GZi compressed files as well.
And there's also Z-More and Z-Cat and Z-Diff and Z-CMP which are the GZi compression counterparts
to the cat-diff and CMP programs respectively. These programs are part of the GNU version of the
GZIP package and should be installed when you install GZIP. But wait there's more. There are also similar
programs for other types of open source compression formats such as BZIP 2 format and the newer
XZ format. Instead of pre-fixing each command with Z you would instead use BZ or XZ as pre-fixes
to the same commands mentioned previously. So for example, BZ-Less and XZ-Less.
According to an early change log from the GNU GZIP source, Z-Less and some of the other
related scripts were first added to the GZIP source on October 14, 1998 by Paul Eger.
They might have an earlier origin though. And finally, but not least, we have the last command. I
literally mean a command that's called last LATST. This program has its origins from the early days
of Unix when systems ran on big monolithic servers that many people logged into from teletype
terminals and video terminals. It was very helpful to system administrators or curious users as to who
recently had logged into a system. To use last, you simply can run it and it will print every entry
in its log. But that can be somewhat overwhelming depending on your log rotation schedule or
popularity of the machine. So you might want to at least supply it with a username to search for
or an argument like the word reboot to see the previous reboot times in the log. You can also
limit the number of entries shown by specifying an option of a dash followed by a number. So dash 10
would show the last 10 log in. In the output of the command, you'll see multiple columns. First,
the username followed by the terminal device they're attached to. If the connection was from
a remote system, the next column will be an IP address. If it's local, you might see colon 0,
if it's say a x-windows log in. The last column showed the initial log in date and log out
time followed by an elapsed time. If the user was logged in over multiple days, you'll see something
like the number of days plus the hours and minutes. In my research of the Unix Heritage website at
TUHS.org, I found that the program last was originally written in February of 1979 by Howard Katseff
and included in the second release of the Berkeley software distribution or BSD back in May of 1979.
After some extensive digging and older versions of the Wikipedia article for UTIL dash Linux
and using Archive.org, I found that the version of last used in Linux distributions was originally
ported in late 1992 by Michael Hart with some changes by Peter Orbeck. Sorry if I don't get those names
right. Both of these people seem to work on this at the start of their careers at the time.
The package it was included in was originally called ADM UTIL, but later became part of UTIL Linux
and then in the late 2000s, UTIL Linux dash NG after development of UTIL Linux Stoll.
Thanks for listening today as we cover some uncommon commands. If you have a favorite use for
one of these commands I mentioned, I'd love to hear about it in the comments on the HDR website.
Take care and I'll talk to you again soon. Bye.
You have been listening to Hacker Public Radio at Hacker Public Radio.org.
Today's show was contributed by a HPR listener like yourself.
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Unless otherwise stated, today's show is released under a Creative Commons
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