Questions specifically about Linux but not specific to a particular distribution. If the question could apply to any Unix-like system, specify your Linux distribution in the body of your question but do not use the /linux tag.

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2
votes
1answer
2k views

dhcp: way to check the online status of the device

On Linux there is the file /var/lib/dhcpd/dhcpd.leases. I need to determine, for the devices for which information contained in this file, whether the device is online at a given moment. Is there any ...
3
votes
1answer
546 views

Internal microphone not working.. again (Fedora 20, KDE, HP 8460p)

Unfortunately I have yet another "adventure" with my internal microphone. Everything is un-muted in alsamixer, as well as in pavucontrol. It is not the first time it stopped working, but now - for ...
5
votes
3answers
2k views

Command similar to netstat -np but grouped by state and PID?

Is there a command similar to netstat -np but grouped by state and PID? I'd like to know the current count of server connections in a particular state grouped by Programs. similar to, 102 squid ...
10
votes
3answers
11k views

Prompt user to login as root when running a shell script

The problem I am getting is, when I enter the command, su - root at the beginning of my shell script file, it prompts the user to enter the password and then does NOT continue with the rest of the ...
8
votes
3answers
3k views

What are the minimum root filesystem applications that are required to fully boot linux?

It's a question about user space applications, but hear me out! 3 'applications', so to speak, are required to boot a funcitonal distro of Linux: Bootloader - For embedded typically that's U-Boot, ...
0
votes
1answer
353 views

Rooting Linux via mysql

I have a CentOS 5.6 x86 installed. I have full access to mysql but it seems I have forgotten Linux root password. How I can access the root via MySQL? Is it even possible? Update: MySQL Version is ...
0
votes
2answers
1k views

Kernel does not skip bad blocks when mounting filesystem

I am developing for an embedded Linux application using friendlyARM's micro2440. It runs on a Samsung s3c2440 ARM processor and uses squashfs in its NAND flash. Recently, some flash blocks went bad. ...
0
votes
1answer
45 views

Mixed-source drivers for Linux [closed]

I am making a research on drivers for Linux that may integrate both open and proprietary source code. I am very new to to the field of driver research and not sure how to look for a comprehensive list ...
1
vote
0answers
184 views

How to set Ralink RT5390 into N mode using iw?

I'm working on supporting a new wifi card for my company. This is the first n mode card I've worked with, previously we've used iw to set the cards into either b or g mode as follows: case $mode in ...
1
vote
2answers
444 views

Run jar on startup in all *nix based systems

I have a jar file which I need to run at startup in all distros of Linux. My previous question here, gave me an idea a rough idea on X-servers. Since I wasn't able to perform startup, I moved on to ...
6
votes
3answers
78 views

different passwords depending on plugged-in devices

I would like to have different passwords for my account(s): When (e.g.) a certain USB stick is plugged in then an easy password is to be used. The idea is: If I leave my computer then I take the stick ...
1
vote
2answers
262 views

What are the specific naming conventions for variables in bash shell scripting language? [duplicate]

Is it the same convention as those used in known programming languages such as Java and C? I'm trying to create a lot of variables and I want it to start with a number, but I'm not sure if it's okay.
2
votes
5answers
2k views

Listing files greater than particular timestamp in file name?

I have a directory in linux which has a list of log files where log files get auto generated if some job runs. Each log file gets appended with the timestamp like "JobName_TimeStamp" UPDATED: ...
0
votes
0answers
211 views

Extremely slow CD-ROM burning

When I try to burn a CD-ROM using K3B, the burner slows down from 10x to 0.12x after writing exactly 71MB. Consequently, burning a 142MB live CD takes more than a hour. Why is this happening? The ...
2
votes
1answer
1k views

closing the unwanted file descriptors

I am trying to understand how pipes work . This code snippet is from some website . So my understanding of the program goes like this : When we do pipe(fd) then fd[0]=3 and fd[0]=4 ( assuming only ...
2
votes
0answers
25 views

Intel Xeon stuck at 800mhz CPU Freq on RHEL 6.5 [duplicate]

Currently running into a headache trying to figure out why my CPU speed is stuck as such a low frequency. After doing some research, I found that cpuspeedutil does actually control the state of the ...
1
vote
1answer
242 views

tcsh/vi-mode behavior difference between Solaris and Linux

We have both Solaris and Linux environments at work. We use tcsh as the standard shell for hundreds of users. My question is about vi-mode in tcsh: In Solaris, while I'm typing, I can backspace ...
6
votes
2answers
8k views

Is it possible to get process group ID from /proc?

In "http://stackoverflow.com/questions/13038143/how-to-get-pids-in-one-process-group-in-linux-os" I see all answers mentioning ps and none mentioning /proc. "ps" seems to be not very portable ...
1
vote
2answers
744 views

How to find out the bad block table offset and how to change it in u-Boot

I am facing a similar problem as this: Kernel does not recognize nand bad blocks marked by u-boot I'm using a friendlyARM micro2440 board that contains the s3c2440 ARM processor. u-Boot has found ...
2
votes
1answer
180 views

How to set umask so that directories to be `r-x` and files to be `---`

I want to set the default permissions for newly created directories to have r-x for others and those of newly created files (non-directory files) to have ---. If I set the umask to 2, directory ...
0
votes
2answers
755 views

Unable to telnet public ip on port 80

We are facing a communication problem between the public and our private network. We have a Linux based web server behind a firewall and an internet router. As part of some integration, our web portal ...
3
votes
2answers
2k views

Primary network interface in Linux

I have a server box with two interfaces. One of the interfaces is connected to the internal network, another - to external. I have assigned IP 192.168.1.200 to internal interface (eth0). I have some ...
2
votes
1answer
3k views

iptables based redirect captive portal style

What is a iptables set of rules that will force hosts connected to a access point, that try to access any website (port 80 of any ip or hostname) to be redirected to another device on the network ...
1
vote
1answer
369 views

Madwifi VAP (and wlanconfig) modern equivalent

It appears that the Madwifi project is deprecated, so I am curious if there is a replacement for the wlanconfig utility that allowed users create Virtual APs. I did search for wlanconfig in my package ...
6
votes
3answers
1k views

Which command to force a drive to spin up?

I've looked through the manual for hdparm, sdparm. I know there are arguments to spin down the drive, with -y and -Y. I also know there are arguments to control the power saving features, such as -S ...
2
votes
1answer
1k views

Ubuntu - Booting black screen with purple border

After the installation of Ubuntu, when I try to boot a black screen with a purple box appears without let me see the GRUB menu. Then the screen becomes black and Ubuntu starts booting. Ubuntu is the ...
2
votes
1answer
391 views

How configurable is MPTCP?

I work on embedded Linux devices that usually have hard wired Ethernet as well as cell modem connections. If I were to use MPTCP would it be possible to easily configure the system to use eth0 all ...
1
vote
2answers
333 views

live dd over a mounted read-only root partiton

I'm trying to conceive a firmware update mechanism for a Linux-based embedded system without an additional initrd/initramfs/whatever. From within the running system which has a read-only mounted root ...
0
votes
1answer
1k views

Installing and setting the default desktop environment in Debian

I recently installed Debian wheezy in my laptop using Debian netinst iso image. I would like to install latest gnome desktop environment but mistakenly downloaded the net installation iso and I also ...
4
votes
1answer
3k views

Automatically detect when a file has reached a size limit

I would like to send an email when a file reach a certain size limit. The only way I thought of doing this is by doing a cronjob which will check the file size and send the email if the file is ...
5
votes
1answer
817 views

Why does readelf show “System V” as my OS instead of Linux?

I compiled a small C program (2 lines of codes) with gcc to try to understand ELF file format. Doing a readelf -h on the object file, I have in the header : OS/ABI: UNIX - ...
0
votes
0answers
2k views

Archive (Compress) giant folder in Linux using command line without termination

Well, I'm just trying to compress a whole directory (infact giant!) under Linux using a terminal. The entire folder size is about 7 GB. I've used below command to create the archive. tar -zcvf ...
1
vote
2answers
918 views

Porting jvm into the kernel space?

Currently I am playing with the idea of a jvm running in the kernel space, as a (maybe linux) kernel module. I see a lot of advantage of the idea. Of course the biggest advantage of a such system ...
1
vote
4answers
234 views

How to set the process won't be terminated when the terminal stops

[Edit] Make it simple. I invoked java xxx... on Machine A using putty to connect from Machine B. However I cannot reach Machine B. How can I connect Machine A from Machine C to set the running ...
1
vote
0answers
54 views

Get log from kernel while loading

There is a arm/omap2-based device without ethernet, UART ports. It has usb connection with host, numeric keyaboard, LCD display. There is working U-Boot and kernel images for this. I'm trying to ...
4
votes
2answers
604 views

Can iptables rules manipulate IP sets?

In iptables-extensions(8) the set module is described and it is discussed that it is possible to react to the presence or absence of an IP or more generally a match against an IP set. However, it ...
2
votes
1answer
134 views

Possible to move boot files?

I just bought an external hard drive that's 1TB. I formatted my laptop and burned Linux to it. The thing is, I also use my hard drive for other things. Can I move these boot files into a custom ...
1
vote
1answer
5k views

how to update Records using nsupdate?

We know that we can update a record (its IP) by doing this steps: nsupdate server ns.bar44.com zone bar44.com update delete somehost.bar44.com. A update add somehost.bar44.com. 86400 A 10.10.10.1 ...
5
votes
2answers
3k views

SSH Login doesn't work using a key Without Password?

Agent admitted failure to sign using the key I'm working on centos6.5(32bit) and I have tried to ssh log in without Password Using ssh-keygen & ssh-copy-id? the steps that I have done: first I ...
2
votes
1answer
348 views

How to check and set “rhash_entries” parameter?

I'm reading this article, and it says: rhash_entries is the size of the hash table. If you don't specify it on the kernel command line, it is computed dynamically based on the memory available on ...
2
votes
0answers
135 views

Debian: pulseaudio sink volumes syncing?

Running Debian jessie with pulseaudio, sometimes I would use pavucontrol to adjust volumes of different applications at varying levels. Then when I would forget about it and adjust the volume using ...
0
votes
0answers
570 views

PHP mail() and Debian Wheezy Not Working

I am currently running my on debian wheezy with php5 installed. I was trying use the mail() function, and I realised that I will require a MTA/exim installed before it will be possible because the ...
11
votes
4answers
19k views

How long has my Linux system been running?

Is there a command I can type in a terminal that will tell me the last time a machine was rebooted?
3
votes
5answers
2k views

Listing directories based on size from largest to smallest on single line

I can use the following command to get a list of directories and their sizes and sort them from largest to smallest (in the example I renamed the directories to numbers to make this easier to ...
3
votes
2answers
2k views

Start zsh with a custom zshrc

I want to be able to start zsh with a custom rc file similar to the command: bash --rc-file /path/to/file If this is not possible, then is it possible to start zsh, run source /path/to/file, then ...
2
votes
3answers
6k views

What commands are available in the %pre section of a Kickstart file on CentOS?

Environment: CentOS 5.5 and 6.4 I have a request to analyze the hardware before installation to make sure our customers don't install our software on sub-standard server hardware. For example, ...
2
votes
1answer
198 views

Capture symbolic link into Unix/Linux variables

Say I have a folder with a series of symbolic links: ussdv103:en195d; default$ pwd /oradba/app/oracle/admin/database1 ussdv103:en195d; default$ ls -ltr exp -> ...
1
vote
1answer
3k views

How can average run queue length be 1 but load average is almost zero

(I originally posted this on Stack Overflow - advised to move it to here). On fedora 17 when i run the sar command to view the load average activity it almost always shows a run queue length of 1 ...
0
votes
0answers
35 views

If a buggy application underperforms, it it possible server tuning could have no affect?

To set the stage, imagine if you will: A read-heavy Tomcat Application with MySQL on Red Hat Enterprise Linux with some problematic Java Class files which resulted in the application performing a ...
2
votes
1answer
112 views

Failed to open netctl@.service configuration file

I have installed Network Manager, I don't have netctl installed. Whenever I boot my Linux computer I get the following error message: systemd[1]: Failed to open configuration file ...