/dev/chat - 2015-03-22

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2:07 AM

These are comments on the content of your answer - which I'm pretty sure is inaccurate in at least those two respects. I do appreciate the welcome, though. — mikeserv 12 mins ago

Or he could read the manual and see that my answer is accurate in both respects. But that's too much to expect from him.

@terdon @MichaelMrozek Could you please go back to enforcing that comment moratorium? mikeserv has been better-behaved lately, but most of his comments to me are still troll bait, designed to shout to the world that I'm wrong rather to make valid points or genuine enquiries.

Even when he isn't insulting, there's just no possible dialog with him.

4 hours later…

6:09 AM

I have a question about whether it is ok to use a third party toner cartridge in my printer. This is one thing that is available here -

zilla.co/in/en/…

Someone wrote here:

tomshardware.com/forum/…

"I looked into this a week ago and from what I can see the big deal with toner is 1. how it's made - either it's been milled (crushed from big blocks using big rollers) or grown chemically. Milled toner has lots of sharp edges on the toner as the crushing rollers tend to leave sharp edges, where chemically made toner tends to be like little smooth surface spheres.

One slowly grinds against the insides of your printer, the other is much nicer to it."

I have no idea whether this is accurate. Would a question about this be on-topic anywhere on the SE network?

Superuser might be.

OK, looks like someone already asked this:

1

Q: Is using generic toner detrimental to laser printers?

Printer manufacturers usually recommend that you only use their branded, OEM toner cartridges in their products but generic ones are commonly available for far less cost. Print quality will of course vary between different brands/makes/models and personal experiences, so that discussion is one o...

8 hours later…

1:52 PM

Should I use "/usr/bin/ssh-askpass" as sudo askpass helper for bash script (for running gui application as root) or not?

@Pandya Why? That's for asking for ssh passwords. What exactly are you trying to do?

@Pandya from man ssh-askpass: ".. is a GNOME-based passphrase dialog for use with OpenSSH"

ie. I don't see why it would help with somethimg requireing sudo

@Anthon That's ssh-askpass-gnome, there's also ssh-askpass which is not GNOME

But you might just want to do ssh -X root@localhost your_gui_app

@terdon That is what my man page gave back. And I think gnome-ssh-askpass is installed as ssh-askpass.

@terdon I needs password asking graphical (GUI) program while running bash-script or command as root. (terminal is hidden or not open for password prompting)

Or another way is to use "zenity --password" as sudo askpass helper?

I am talking about sudo -A <command>.

2:01 PM

@Pandya why not use gksudo?

@Anthon let sleeping dogs lie

@Anthon apt-cache search showed me two separate packages.

And I;m deleting those last lines in case we wake the sleeping dragon.

@Gilles ok, sorry for that

@terdon what is the use of sudo -A? (I don't want to use gksudo because it seems slower that sudo!)

@Pandya To provide an alternate way to enter a password as far as I know.

@Pandya gksudo needs to do more work than sudo: it has to display an extra window. But there's a user interaction anyway, so such a tiny performance difference is irrelevant.

2:04 PM

And yes, the man page does suggest ssh-pass but that, presumably, is for launching an ssh session.

Isn't pkexec the way we're supposed to do these things now?

Although a better question @Pandya is why are you writing a script that needs graphical root access?

2:17 PM

@terdon currently (forgot the script), I've set shortcut key to open Nautilus as Root and the command is gksudo nautilus but I want to use sudo instead. So, It is required to prompt password graphically. And I think one solution is to use sudo -A nautilus and hence I've to provide "askpass helper". And I want to know if Should I use /usr/bin/ssh-askpass or /usr/bin/zenity --password?

Dear God, why do people want to run file managers as root?

@Pandya 1) What Briam said, don't run that as root. 2) Why not use gksudo? 3) I don't think that ssh-askpass has a GUI so yes, the zenity approach, if it works, would be better.

@terdon OK

@terdon BTW, ssh-askpass has GUI:

user image

@Pandya Ah, OK. Cool. But will that pass it to sudo? I don't understand why you're not using gksudo, that's what it's for.

put this out of his misery unix.stackexchange.com/q/191790/41104

2:29 PM

visit man sudo and look for -A, --askpass

@Pandya is there a good reason why you need to couple sudo with a GUI element?

@Pandya Yes, I know, but that doesn't mean that it works when you're not trying to run ssh-add.

It might, I just don't know.

@Pandya "I ocsiononaly"?

@Braiam I occasionally uses Nautilus as root at my risk with great care.

0

Q: Which software to put two wifi connection together? (Linux)

I've two Wi-Fi adapters: Built in adapter - Quallcom Atheros. It is connected to router1 and gives approximately 350 kb/s. External adapter - Ralink. It is connected to router2 and gives approximately 300 kb/s. Which software would help me to get them together? I mean my speed would be 350...

linux wifi connection-speed

This is really a how-to question that should be on Unix & Linux, rather than a which-software question that could be either on Unix & Linux or Software Recommendations

2:41 PM

@Gilles Is that even possible? Can two NICs be combined that way?

But we don't have a policy that would allow us to rule it off-topic on SR, so I can't migrate it to where people could answer it

@terdon of course

@Gilles Really? Huh, cool.

So two working NICs, each with their own IP or shared IP somehow?

Why not use just one NIC?

@FaheemMitha because both paths have limited bandwidth, he wants to use the combined bandwidth

@terdon depends on what he's trying to do

Are these two separate internet connections, or do paths to the two routers converge to a point that has a single public IP address? — Gilles ♦ 50 secs ago

@Gilles So it is actually possible to have two NIC, both on the same network, one at 102.168.1.5, the other at 192.168.1.6 and the machine downloading through both of them?

I really should read up on networking at some point.

2:47 PM

linux-ip.net/html/adv-multi-internet.html looks like a good guide for splitting connections between two internet links

Link aggregation

In computer networking, the term link aggregation applies to various methods of combining (aggregating) multiple network connections in parallel in order to increase throughput beyond what a single connection could sustain, and to provide redundancy in case one of the links should fail. Further umbrella terms used to describe the method include port trunking,link bundling, Ethernet/network/NIC bonding, or NIC teaming. These umbrella terms encompass not only vendor-independent standards such as Link Aggregation Control Protocol (LACP) for Ethernet defined in IEEE 802.1AX and IEEE 802.1aq or the...

and ^^^^ is an overview of splitting at the packet level

@Gilles Oh

@Gilles Wow. Simple it ain't. Thanks.

I assume support for this is required in the kernel.

Is that what happens automagically if I'm connected via my wireless NIC and also plug in an ethernet cable? I had always assumed that the fastest of the two is used.

@terdon Unlikely.

I don't see how this could be default behavior.

2:52 PM

@terdon no, that won't happen automagically.

No idea but I don't really know the first thing about this. Only that I have often had both NICs active and have used the interweb. The details escape me.

@Gilles So if I'm connected via both wireless and cable, the system will choose one of the two to use?

I routinely plug in an Ethernet cable while the wifi is active, and that gives me the wired connection as the default route. I haven't looked why the wired connection is prefered.

@terdon I imagine it would just stay with the one you are already using by default.

But it depends on the setup.

@Gilles how can you tell which one it is using?

I believe is last added to the route table

@FaheemMitha default route

@Braiam But if I turn on the wifi while I have a wired connection, the wifi doesn't take over the default route.

I use NetworkManager. It probably prioritizes wired connections over wireless.

2:56 PM

@Gilles How does one find out what the default route is?

@Gilles that's why I said "last added"

wait, what?

yeah, NM may be to blame

There has been quite the efflorescence of SE sites. I didn't even know graphicdesign.stackexchange.com existed.

@FaheemMitha run route and look at the line that starts with default

@Gilles Ok. Thank you.

@Braiam I don't blame it: that's a sensible thing to do

3:02 PM

Hello, what difference between using/adminstrating linux/unix books and shell scripting/programming books? Is the latter only part of the former?

@Tim Yes.

what else that are not shell programming/scripting?

@Tim Umm. Loads?

are commandline and shell programming the same topic?

Administering users/packages/networking etc. Shell scripting can be part of administration but it can also have absolutely nothing to do with it.

@Tim No.

The commandline is an interface. You can use it to launch software. Shell scriptping is a programming language.

It just happens to be a language spoken by the command line. In a way.

3:06 PM

what is shell not about administration?

@Tim ?

@Tim huh?

I am trying to choose some books on bash or other *sh, but the books are titled in different ways. I don't know which one to choose

Classic Shell Scripting: Hidden Commands that Unlock the Power of Unix Paperback – 26 May 2005
by Arnold Robbins (Author), Nelson H. F. Beebe

A practical guide to Linux commands, editors, and shell programming, by Mark G. Sobell.
A practical guide to Linux by Mark G. Sobell. 1997

The Linux Command Line By William Shotts

If you want a book on shell scripting, buy a boog on shell scripting, not one on UNIX administration.

Linux Command Line and Shell Scriptin...
by Richard Blum

Learning the bash Shell: Unix Shell P... by Cameron Newham

Ken Burtch, Linux Shell Scripting with Bash, 1st edition, Sams Publishing (Pearson), 2004, 0672326426.

3:09 PM

search.oreilly.com/?q=shell&x=0&y=0

David Medinets, Unix Shell Programming Tools, McGraw-Hill, 1999, 0070397333.

As I said, if you want one that is a bout the shell programming language, buy one that focuses on that and not on system administration.

@Tim This seems like a safe bet.

@Tim Or this one.

Just anything with "bash" or "shell" in the title. Administration is a whole different thing.

Personally, I would get the O'reilly bash book. They (O'reilley) tend to be excellent .

shop.oreilly.com/product/9780596009656.do

I often saw there are different lines of OReilly books: Learning xxx, Programming xxx, xxx in a nutshell, xxx pocket reference, xxx cookbook, ....

it seems learning xxx is for absolute beginners, and programming xxx is a sequel to learning xxx?

Thanks. How do you like OReilly's Learning bash, versus Advanced Bash-Scripting Guide, Mendel Cooper (ABS Guide), versus Bash Reference Manual, by Ramey ?

@Tim Sobell's books are pretty nice. I have A practical Guide to Linux, I think. Or maybe a practical guide to unix.

However, I don't really think you need books at all.

I haven't bought a computer book in many years. In any case, check it out before you buy.

The last one I got was Nemeth's book on Unix Admin. And I never look at it.

but faheem, as terdon said, admin books and shell books are different.

3:21 PM

@Tim I don't know. I've just very much enjoyed every O'reilley book I've read.

@Tim sure they are. what did you want again?

become better at shell scripting/programming

@Tim then write shell and program. buying books really isn't that useful.

I have a fair number. I rarely look at them.

There's lots of stuff on the net these days. Some of it peer reviewed.

I download not buy any more

@Tim oh

The #bash IRC channel on freenode is quite helpful. and they have some high powered wiki associated with it.

3:26 PM

Any books good at explaining symlinks usage?

is that shell or admin topic?

@Tim dunno. what do you want to know about symlinks?

everything about using them properly and cleverly

@Tim I'm not sure what you mean.

Are symlinks more of shell or admin or something else?

I found symlinks can do many useful things. I don't know much about them

I always get some vague ideas and questions, whenever I have time to reflect on what I have encountered.

Oh good, mikeserv has woken up.

He's a really successful troll. He makes me want to delete my U&L account just so that the stream of comments stops.

3:34 PM

what happened? I thought mikeserv was highly reputed ...

what kinds of books will I likely to find more about symlinks?

@Gilles please don't.

echo what faheem said.

@Tim I don't think there is much to know about them. They are what they are. What you do with them is up to you.

It's like wanting to read a book about hammers.

There is the underlying filesystem implementation of symlinks and suchlike, which is no doubt non-trivial. But I doubt that will help you make use of them.

Just curious- is there anyone here who actually buys computer books?

Tanenbaum's books are great

I have only read the beginning of some of his books, and I feel he organized things better than most others' books

@Tim Tanembaum is a computer scientist. He writes books about Operating Systems, as far as I know.

@terdon What, all of them?

4:10 PM

Question: is there a good way to grep through a bunch of files looking for email addresses? I think one can assume strings of the form xxx@xxx.xxx, where the xxx are neither @ or .. Unfortunately that probably requires regexes.

@FaheemMitha No, just those I've read which aren't many.

@terdon ok

3 hours later…

7:41 PM

@FaheemMitha why using regex is unfortunate?

@Tim Well, I don't know it.

[^.]*@[^.]*\.[^.]*

@Tim Yikes. What do I do with that?

@FaheemMitha . is very common in the username part of email addresses, why do you want to omit it?

using gedit and regex plugin

7:44 PM

@Gilles Oh, hmm. I guess I don't.

@Tim I'll need to run this over a bunch of files, probably.

grep -E?

Note that if you want to capture all valid email addresses, it's A LOT more complex than that, but you'll get a lot more false positives

@Tim probably.

ex-parrot.com/~pdw/Mail-RFC822-Address.html

@Gilles Well, first approximations are fine.

@Gilles eek

7:46 PM

Is your job admin?

@Tim who, me? No, I was just trying to help someone with a question.

The original reason is probably redundant now - but i doesn't hurt to know how to do these things.

[-+.0-9A-Z_a-z]+@[-.0-9A-Za-z]+[0-9A-Za-z] should be a decent approximation in practice

@Gilles Ok, and how do I use it? preface with grep -E?

@FaheemMitha grep -Eo '[-+.0-9A-Z_a-z]+@[-.0-9A-Za-z]+[0-9A-Za-z]'

Maybe a -R too.

7:48 PM

warning: untested

@Gilles does that automatically recurse?

@Gilles as long as it doesn't send my computer up in flames.

what if without -o? @Gilles

@FaheemMitha you then need -r

@Tim ok

do you like to learn regex?

8:03 PM

@Tim Not especially.

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