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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15
votes
2answers
479 views

Can I list the filesystems a running kernel can support?

I'm trying to detect what filesystems a kernel can support. Ideally in a little list of their names but I'll take anything you've got. Note that I don't mean the current filesystems in use, just ones ...
15
votes
2answers
5k views

Why does high disk I/O reduce system responsiveness/performance?

I never quite understood why high disk I/O slowed the system so much. It's strange to me because I would expect the slow-down to affect only those processes dependent on the hard/optical drive data, ...
15
votes
7answers
28k views

Unix/Linux undelete/recover deleted files

Is there a command to recover/undelete deleted files by rm? $ rm -rf /path/to/myfile How can I recover myfile? If there is such a tool how can I use it?
15
votes
2answers
2k views

Linux: Total swap used = swap used by processes +?

So, I'm trying to do some investigation on where does swap use come from in a system with high swap usage: # free total used free shared buffers cached Mem: ...
14
votes
3answers
972 views

Why do Linux people always say to read the manual? [closed]

Why do Linux people always say to read the manual when it would be so much easier to just give you an answer? There's no manual! It didn't come with one.
14
votes
2answers
1k views

Accidently created a file called -X, how can I delete it? [duplicate]

Possible Duplicate: How do I delete a file whose name begins with “-” (hyphen a.k.a. dash or minus)? Like an idiot, I ran this command: tar -cf -X awstats-icon icon ...
14
votes
5answers
7k views

What is the difference between ls and l?

I accidentally typed l instead of ls today and found that the command still printed a list of the files in my current directory. Trying l --help brings up the help file for ls suggesting that l is ...
14
votes
4answers
994 views

Why not always use rsync?

I wanted to ask is there any reason not to use rsync for everything and abandon cp? I wasn't aware of rsync and now I don't know why cp is ever needed.
14
votes
10answers
2k views

What linux is best suited for people new to computers?

What would be the easiest linux for people who are new to computers? The computers here have 256Mb RAM with 40GB hard-disks. UPDATE: Most of them apparently have more than 265MB of RAM with some ...
14
votes
5answers
3k views

Getting information on a machine's hardware in Linux

How can I check what hardware I have? (With BIOS version etc.)
14
votes
6answers
11k views

Execute a specific command in a given directory without cd'ing to it?

Is there a way to execute a command in a different directory without having to cd to it? I know that I could simply cd in and cd out, but I'm just interested in the possibilities of forgoing the extra ...
14
votes
3answers
799 views

Move files and change ownership at the sametime

On Linux (Debian, Ubuntu Mint...), Is there any option command or something that I can use to transfer files to another user without having to do : sudo mv /home/poney/folderfulloffiles ...
14
votes
3answers
2k views

Why don't you need to update drivers? (Or do you?)

In my life I've not once updated drivers on any of my Linux systems, though they have all been desktops. A friend was asking me why one does not need to update Linux drivers and I found myself unable ...
14
votes
3answers
4k views

(How) can I create a tmpfs as a regular (non-root) user?

The distribution is an Ubuntu server running the 2.6.35-30 Linux kernel. I would like to have a directory that sits completely in memory. Is this possible without root privileges?
14
votes
4answers
11k views

What is the equivalent of Active Directory on Linux

I have a couple of machines at home (plus a number of Linux boxes running in VMs) and I am planning to use one of them as a centralized file server. Since I am more a Linux user rather than a ...
14
votes
3answers
21k views

Yum: How can I view variables like $releasever, $basearch & $YUM0?

I am setting up a yum repository, and need to debug some of the URLs in the yum.conf file. I need to know why is Scientific Linux trying to grab this URL, when I was expecting it to grab another URL: ...
14
votes
3answers
4k views

Understanding /dev and its subdirs and files

$ ls -l /dev/stdin /dev/fd/0 lrwx------ 1 tim tim 64 2011-08-07 09:53 /dev/fd/0 -> /dev/pts/2 lrwxrwxrwx 1 root root 15 2011-08-06 08:14 /dev/stdin -> /proc/self/fd/0 $ ls -l /dev/pts/2 ...
14
votes
4answers
462 views

How do I learn what I can do with /proc and /sys

I'd like to know more about the advanced uses of the /proc and /sys virtual filesystems, but I don't know where to begin. Can anyone suggest any good sources to learn from? Also, since I think sys has ...
14
votes
2answers
26k views

What is the difference between ioctl(), unlocked_ioctl() and compat_ioctl()?

Going through the linux 2.6.36 source code at lxr.linux.no, I could not find the ioctl() method in file_operations. Instead I found two new calls: unlocked_ioctl() and compat_ioctl(). What is the ...
14
votes
2answers
40k 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 ...
14
votes
3answers
8k views

How to read environment variables of a process

Linux's /proc/<pid>/environ does not update (as I understand it, the file contain the initial environment of the process). How can I read a process's current environment?
14
votes
2answers
2k views

Can the same ext4 disk be mounted from two hosts, one readonly?

I know that mounting the same disk with an ext4 filesystem from two different servers (it's an iSCSI vloume) will likely corrupt data on the disk. My question is will it make any difference if one of ...
14
votes
4answers
1k views

Corruption-proof SD card filesystem for embedded Linux?

Recently we had a rather unpleasant situation with our customer - Raspberry Pi based "kiosk" used to display remote sensing data (nothing more fancy than a kiosk mode browser displaying a ...
14
votes
1answer
1k views

What is Linux doing differently that allows me to remove/replace files where Windows would complain the file is currently in use?

The example I have is Minecraft. When running Bukkit on Linux I can remove or update the .jar files in the /plugins folder and simply run the 'reload' command. In Windows, I have to take the whole ...
14
votes
1answer
4k views

init process: ancestor of all processes?

I have always learned that the init process is the ancestor of all processes. Why does process 2 have a PPID of 0? $ ps -ef | head -n 3 UID PID PPID C STIME TTY TIME CMD root ...
14
votes
2answers
11k views

Reply on same interface as incoming?

I have a system with two interfaces. Both interfaces are connected to the internet. One of them is set as the default route; a side effect of this is that if a packet comes in on the non-default-route ...
14
votes
2answers
55k views

How to find the installation path for a software under linux?

Under linux, I launch a software by typing, e.g., fluidplot. How can I find the installation path for this software?
14
votes
3answers
5k views

Full disk encryption with password-less authentication in Linux

I have a fairly standard disk encryption setup in Debian 5.0.5: unencrypted /boot partition, and encrypted sdaX_crypt that contains all other partitions. Now, this is a headless server installation ...
14
votes
3answers
21k views

Can I connect to Windows machine from Linux shell?

I can connect to Linux machines from Windows using PuTTY/SSH. I want to do the other way round - connect to a Windows machine from Linux. Is this possible?
14
votes
3answers
4k views

How to detect memory type under Linux?

Which Linux utility can tell me if I have registered or unbuffered ECC memory in my server? Lshw and dmidecode do not work for me; dmidecode provides no information about registered vs. unbuffered: ...
14
votes
3answers
2k views

How to use three monitors on a laptop?

I have a laptop running Ubuntu 9.04 with a dual-head setup: laptop panel + external monitor. I'd like to add another monitor but the laptop has a single VGA port, so my question is: what are my ...
14
votes
1answer
1k views

Shebang line with `#!/usr/bin/env command --argument` fails on Linux

I've got a simple script: #!/usr/bin/env ruby --verbose # script.rb puts "hi" On my OSX box, it runs fine: osx% ./script.rb hi However, on my linux box, it throws an error linux% ./script.rb ...
14
votes
6answers
15k views

Check if folder is a mounted remote filesystem

What is the best way (reliable, portable, etc.) to check if a given folder is on a mounted remote (nfs) filesystem within a shell script? I am looking for a command that would look like: ...
14
votes
1answer
18k views

How can I set up logrotate to rotate logs hourly?

According the the Unix and Linux Administration Handbook and man, logrotate has options for daily, weekly, and monthly, but is there a way to add an hourly option? This blog post mentions you can set ...
14
votes
6answers
8k views

Correlating /var/log/* timestamps

/var/log/messages, /var/log/syslog, and some other log files use a timestamp which contains an absolute time, like Jan 13 14:13:10. /var/log/Xorg.0.log and /var/log/dmesg, as well as the output of $ ...
14
votes
1answer
12k views

How to use Linux kernel driver bind/unbind interface for USB-HID devices?

First background. I am developing a driver for Logitech game-panel devices. It's a keyboard with a screen on it. The driver is working nicely but by default the device is handled by HID. In order to ...
14
votes
3answers
4k views

Are multiple @daily crontab entries processed in order, serially?

I want two jobs to run sometime every day, serially, in exactly the order I specify. Will this crontab reliably do what I want? @daily job1 @daily job2 I'm assuming they run one after the other, ...
13
votes
4answers
8k views

What is the meaning of $? in a shell script?

When going through one shell script, I saw the term "$?". What is the significance of this term?
13
votes
6answers
1k views

Can a Linux command have capital letter(s)?

Can a Linux command have capital letter(s)? I know it's supported but i want to be sure if it's a "problem" or considered "not a good thing"?
13
votes
5answers
9k views

Can we get compiler information from an elf binary?

Is there some chance to know how a binary was built, under Linux? (and or other Unix) Compiler, version, time, flags etc... I looked at readelf and couldn't find much, but there might be other ways ...
13
votes
4answers
39k 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 ...
13
votes
6answers
881 views

How to achieve portability with sed -i (in-place editing)?

I'm writing shell scripts for my server, which is a shared hosting running FreeBSD. I also want to be able to test them locally, on my PC running Linux. Hence, I'm trying to write them in a portable ...
13
votes
3answers
2k views

How can I de-fragment a drive using Ubuntu?

Is it necessary to defrag drives in Ubuntu? If so, how do I do it and how often should it be done?
13
votes
6answers
6k views

What's the best way to partition your drive?

I usually install Linux on a single partition since I only use it as a personal desktop. However every now and then I reinstall the box and what I simply do is to move my files around with an ...
13
votes
3answers
789 views

Do different distros (but same kernel ver) have same hardware support

As far as I know the device drivers are located in the Linux kernel. For example let's say a GNU/Linux distro A has the same kernel version as a GNU/Linux distro B. Does that mean that they have the ...
13
votes
3answers
17k views

Which users are allowed to log in via SSH by default?

When I set up my Debian 6, I was wondering, which users apart from root whose password I know can log into my system via SSH? When I install Apache 2 a user called www-data gets created. Does this ...
13
votes
4answers
1k views

Is there any reason why I get ^[[A when I press up arrow at the console login screen?

Whenever I'm at the console login, I press up arrow intentionally to see the previously typed commands. But I see this ^[[A. But when I press Ctrl Alt Print Screen Scroll Lock Pause Break Page Up ...
13
votes
6answers
12k views

How can I page up or down in tmux with Terminal.app?

I have tmux installed. But I can not scroll up or down. I.e. as soon as I tmux I get only a portion of the screen and can not scroll up. crtl-b + Page Up does not work since I am in Mac and I can not ...
13
votes
3answers
3k views

Automatically rename files when they are placed in a specific directory

Is it possible to automatically rename a file when it's placed in a specific directory? For example I have a directory named "dir0".I move or copy a file named "file1" to "dir0".then "file1" should ...
13
votes
2answers
1k views

How secure is keeping non-root owned scripts in /etc/init.d?

I have an application which runs as a daemon and is controlled by a script in /etc/init.d Sometimes we need to change some parameters of startup/control of these scripts and then restart the daemon. ...