Questions specifically about Linux, as opposed to Unix-like systems in general, or to questions about a specific distribution or program.

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12
votes
7answers
6k views

What's the best way to format a HDD in Linux in order to leave no trace?

I'm running Debian and need a way to format the entire hdd in order to not leave any trace on it because I want to donate it to a friend. So what will be the best way in order to format it? If I ...
11
votes
2answers
8k views

How to re-mount a USB stick after unmounting from Nautilus without disconnecting it?

I find that in order to re-mount a USB stick, I have to physically disconnect it, and then re-connect it. How can I do this without such tiring physical action?
8
votes
3answers
3k views

How can I monitor disk I/O in a particular directory?

I've got a few processes with a known name that all write to files in a single directory. I'd like to log the number of disk block reads and writes over a period (not just file access) to test whether ...
7
votes
3answers
3k views

Using notify-send with cron

I am using Arch Linux with KDE/Awesome WM. I am trying to get notify-send to work with cron. I have tried setting DISPLAY/XAUTHORITY variables, and running notify-send with "sudo -u", all without ...
28
votes
4answers
1k views

Execution of possibly harmful program on Linux

I'm writing a program that will test programs written by students. I'm afraid that I can't trust them and I need to make sure that it won't end up badly for the computer running it. I was thinking ...
16
votes
1answer
4k views

What is maximum RAM supportable by Linux?

What is the maximum supportable RAM by Linux? Assume that hardware is/supports 64-bit. Among all Linux distros. Does it go up to 16 exabytes, or is it limited like with Windows which I believe is 192 ...
13
votes
3answers
2k views

Given a git patch id, how to find out which kernel release contains it?

Assume I have some issue that was fixed by a recent patch to the official Linux git repository. I have a work around, but I’d like to undo it when a release happens that contains my the fix. I know ...
13
votes
4answers
42k views

SSH login with clear text password as a parameter?

I need to login to a user that I've created on a remote host running Ubuntu. I can't use an ssh key because the ssh login will happen from a bash script ran within a server that I wont have access to ...
12
votes
2answers
32k views

How to display open file descriptors but not using lsof command

Hi I have read Here that lsof is not an accurate way of getting the number of File Descriptors that are currently open. He recommended to use this command instead cat /proc/sys/fs/file-nr While ...
11
votes
1answer
19k views

Manually generate password for /etc/shadow [duplicate]

I need to manually edit /etc/shadow to change the root password inside of a virtual machine image. Is there a command-line tool that takes a password and generates an /etc/shadow compatiable password ...
11
votes
9answers
4k views

What is the smallest possible Linux implementation?

What are the bare minimum components for a Linux OS to be functional, and that I can use as a base to expand and improve as I learn Linux and my understanding and needs grow?
10
votes
3answers
7k views

How to run a script with systemd right before shutdown?

What do I need to put in the [install] section, so that systemd runs /home/me/so.pl right before shutdown and also before /proc/self/net/dev gets destroyed? [Unit] Description=Log Traffic [Service] ...
10
votes
2answers
6k views

Linux: Writing a watchdog to monitor multiple processes

A few years ago, a coworker came up with an elegant solution for a watchdog program. The program ran on Windows and used Windows Event objects to monitor the process handles (PID’s) of several ...
8
votes
2answers
4k views

Installing a package locally to a user - best practices?

I want to install Git locally to a user on a RHEL server (I don't have root access) What would be your cleanest/ most organized way of installing software to a local user account? Installing ...
5
votes
1answer
2k views

How to get Oracle java 7 to work with setcap cap_net_bind_service+ep

I am trying to grant the java executable the right to open ports below 1024 on Linux. Here is the setup /home/test/java contains the Oracle Server JRE 7.0.25 CentOS 6.4 Here is what getcap ...
2
votes
1answer
278 views

what are the different ways to set file permissions etc on gnu/linux

On Unix a long time back I learned about chmod to set permissions and to allow programs to gain privileges. I have recently discovered extra commands on GNU/Linux: chattr, setfacl, setcap. Are there ...
2
votes
2answers
552 views

Resources to learn linux architecture in detail? [closed]

I want to learn the Linux file hierarchy and how the OS works at a deeper level. Are there any ebooks or webpages to learn that?
17
votes
3answers
5k views

When should I use a trailing slash on a directory? [duplicate]

Possible Duplicate: How linux handles multiple path separators (/home////username///file) Most commands I use in linux behave exactly the same whether I include the trailing slash / ...
17
votes
6answers
6k views

How does Linux kernel compare to microkernel architectures?

I read once that one advantage of a microkernel architecture is that you can stop/start essential services like networking and filesystems, without needing to restart the whole system. But considering ...
14
votes
2answers
43k views

Remove GPT - Default back to MBR

I keep receiving this error: Warning!! Unsupported GPT (GUID Partition Table) detected. Use GNU Parted I want to go back to the normal MBR. I found some advice here and did: parted /dev/sda ...
13
votes
3answers
640 views

Contents of /proc

Is there a site someplace that lists the contents of /proc and what each entry means?
11
votes
2answers
1k views

What makes an operating system “Unix-Like”?

I frequently come across the term "unix-like" on many web sites. There is no standard; it is just in the way it behaves. But if I were to develop a kernel from scratch, what would make it considered ...
10
votes
6answers
620 views

Options to show images when on the console

When I am on the console (the tty, the virtual terminal, which you reach with Ctrl+Alt+F1-6, not a terminal emulator), what options do I have to view images, tiff, whatever that's not text?
10
votes
1answer
2k views

Adjusting keyboard sensitivity in a command line terminal?

When using a tty login shell by entering Ctrl-Alt-F1 from an Ubuntu 12.04 install on a laptop the keyboard seems overly sensitive and if my finger lingers for a moment on a button I end up with ...
10
votes
4answers
598 views

How to write a script that effectively determines distro name?

I saw this post on all the different ways to find out what distro is installed, so I'm trying to write a script that tries them all. The possible commands include: $ cat /etc/lsb-release $ cat ...
10
votes
3answers
2k views

How do I log into my Linux laptop if I have forgotten both the login and password?

How do I log into my Linux laptop if I have forgotten both the username and password?
9
votes
5answers
3k views

How to create a file even root user can't delete it

How to create a file even root user can't delete it ?
8
votes
2answers
6k views

Cleancache vs zram?

I have an old laptop here with only 512 MB of RAM. Since a few kernel releases, I am using zram to convert 256 MB of it to a compressed ramdisk which is then used as swap. This has proved to be very ...
8
votes
2answers
3k views

Several questions about file-system character encoding on linux

Due to a lot of file exchange works between Windows (GBK encoding) and Linux (UTF-8 encoding), it will encounter character encoding issues easily, such as: zip/tar files whose name contains chinese ...
7
votes
3answers
22k views

How to rename multiple files in single command or script in Unix? [duplicate]

I have the below list of files aro_tty-mIF-45875564pmo_opt aro_tty-mIF-45875664pmo_opt aro_tty-mIF-45875964pmo_opt aro_tty-mIF-45875514pmo_opt aro_tty-mIF-45875524pmo_opt that I need to rename to ...
7
votes
2answers
3k views

wlan number assignment

How or where does Linux determine the assignment of a network device? Specifically, wlan0 or wlan1 for wireless USB devices. I plugged in a TP USB wireless a while ago, and it was assigned wlan0. I ...
7
votes
9answers
963 views

How to prevent a process from writing files

I want to run a command on Linux in a way that it cannot create or open any files to write. It should still be able to read files as normal (so an empty chroot is not an option), and still be able to ...
6
votes
1answer
917 views

Find out if a specific device is an USB mass storage

Context I'm automating SD card imaging from an existing dd factory image. The SD card is always connected through an external USB card reader and thus appears in the system as a SCSI block device ...
6
votes
3answers
4k views

How to generate initramfs image with busybox links?

Having been directed to initramfs by an answer to my earlier question (thanks!), I've been working on getting initramfs working. I can now boot the kernel and drop to a shell prompt, where I can ...
5
votes
3answers
5k views

How to share files between Linux and Windows?

I am wondering, is there any way to easily share a folder between Linux and Windows?
4
votes
3answers
3k views

Send duplicate packets over two Internet connections

I need to duplicate an RTP stream over two different (non-reliable) Internet connections. On the receiver side, I will probably run a custom program that will use a buffer and rebuild the stream ...
3
votes
1answer
520 views

Writing triggers for mcelog

Just starting to look into mcelog for the first time (I've enabled it and seen syslog output before, but this is the first time I'm trying to do something non-default). I'm looking for information on ...
2
votes
2answers
2k views

Best options for mounting Mac OS X hard drive on my Linux box?

I have a new 3 terabyte external USB hard drive (Seagate ST3000DM001 in an enclosure). I hope to use it on both my iMac (OS X 10.6.8) and my Linux machines (Kubuntu). Right now this drive will ...
15
votes
3answers
16k views

disable transparent hugepages

We are installing SAP HANA in a RAID machine. As part of the installation step, it is mentioned that, To disable the usage of transparent hugepages set the kernel settings at runtime with echo ...
10
votes
4answers
3k views

Batch delete exif info

How can I recursively remove the EXIF info from several thousand JPG files?
9
votes
4answers
7k views

How to shutdown Linux at a specific datetime from terminal?

It seems I can shutdown using sudo shutdown by specifying a time or minutes. Is there a way to specify datetime for shutdown?
9
votes
7answers
12k views

How do I work with GUI tools over a remote server?

I have an Ubuntu server running on EC2 (which I didn't install myself, just picked up an AMI). So far I'm using putty to work with it, but I am wondering how to work on it with GUI tools (I'm not ...
8
votes
2answers
6k views

How to make exported shell variables permanent?

export LD_PRELOAD=/usr/lib/libtsocks.so It's ok that I can export in this way, but how can I make it permanent? I want LD_PRELOAD to still be changed after a reboot. I'm using Ubuntu and Fedora
6
votes
5answers
209 views

Command line expression solver?

I'm looking for a Linux-compatible TTY-based calculator. For example: user@host:~$ calculate > 2 2 user@host:~$ calculate > 8*6-4 44 user@host:~$ calculate > 8*(6-4) 16 Is there anything ...
6
votes
3answers
550 views

Entries I can safely exclude doing backups

I'm planning a backup strategy based on rsnapshot. I want to do a full system backup excluding files and directories that would be useless for the restore to have a working system again. I already ...
6
votes
2answers
839 views

Share keyboard over network as separate device?

I am trying to achieve something similar to this: http://superuser.com/questions/67659/linux-share-keyboard-over-network The difference is that I need the remote keyboard to be usable separate from ...
6
votes
2answers
1k views

How does load average work with modern CPU's?

My understanding of load average lead me to be quite shocked with my current system. The CPU in my workstation is an i7 with hyperthreading enabled, and cat /proc/cpuinfo produces 4 'cpu's. That all ...
5
votes
2answers
2k views

What should I be aware of when installing Linux on a Mac?

I have a Macbook Pro and I am loving it, though I still miss my Linux box, there are many things I need which are not completely compatible with Mac OS X. I heard many stories about installing Linux ...
5
votes
1answer
4k views

How to understand why the packet was considered INVALID by the `iptables`?

I set up some iptables rules so it logs and drops the packets that are INVALID (--state INVALID). Reading the logs how can I understand why the packet was considered invalid? For example, the ...
5
votes
2answers
5k views

iptables port-mirroring

I need to be able to get a copy of packets received on port 8001 to port 8002. I have tried the following but I get an error that --tee is undefined. sudo iptables -t nat -A PREROUTING -p TCP -s ...