19
votes
7answers
67k 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?
18
votes
4answers
7k views

Four tasks in parallel… how do I do that?

I have a bunch of PNG images on a directory. I have an application called pngout that I run to compress these images. This application is called by a script I did. The problem is that this script does ...
17
votes
1answer
12k views

What is meant by mounting a device in Linux?

I've heard the term "mounting" when referring to devices in Linux. What is its actual meaning? How it handling now unlike older versions? I haven't done that manually via the command-line. Can you ...
12
votes
4answers
4k views

Evolution of Operating systems from Unix

Can you explain the evolution hierarchy of operating systems (Linux and Windows) from Unix?
11
votes
2answers
54k views

Can I resize the root partition without uninstalling and reinstalling Linux (or losing data)?

I have started using a machine that has both Debian and Windows 7 installed. However, after installing some programs I started getting a message that there is not enough space. I knew that the system ...
27
votes
10answers
13k views

How to understand what's taking up space?

I'm looking for a linux alternative to WinDirStat. I would like to know what is taking up space on my hard drives. A program that works on console and doesn't require a UI is preferred .
39
votes
2answers
37k views

How do I do a ls and then sort the results by date created?

In what order are the dated ordered by? Certainly not alphanumeric order. ls -lt sorts by modification time. But I need creation time.
30
votes
2answers
11k views

What do the brackets around processes mean?

mark@mark-VirtualBox:~/auto/lib$ ps -Awwo pid,comm,args PID COMMAND COMMAND 1 init /sbin/init 2 kthreadd [kthreadd] 3 ksoftirqd/0 [ksoftirqd/0] 5 ...
18
votes
7answers
778 views

Reading and searching long man pages

I finally got fed up when wanting to read about bash's read and it's -s option with man bash. I found the right spot eventually (around line 4500), but it was a frustrating as usual, since both /read ...
18
votes
3answers
6k views

Determining Specific File Responsible for High I/O

This is a simple problem but the first time I've ever had to actually fix it: finding which specific files/inodes are the targets of the most I/O. I'd like to be able to get a general system overview, ...
34
votes
4answers
4k views

unix, difference between path starting with '/' and '//'

In unix/linux, any number of consecutive forwardslashes in a path is generally equivalent to a single forwardslash. eg. $ cd /home/shum $ pwd /home/shum $ cd /home//shum $ pwd /home/shum $ cd ...
13
votes
2answers
14k views

How to run grep with multiple AND patterns?

I would like to get the multi pattern match with implicit AND between patterns, i.e. equivalent to running several greps in a sequence: grep pattern1 | grep pattern2 | ... So how to convert it to ...
9
votes
2answers
3k views

How to restrict internet access for a particular user on the lan using iptables in Linux

Let's say there are two users on the LAN, A and B. How do I restrict user A from internet access using iptables rules and saving the rules so that after reboot, they are still effective. And suppose I ...
22
votes
2answers
3k views

Where do the files go if you mount a drive to a folder that already contains files?

I just accidentally mounted a new drive to a folder that already contained files. I don't care about them and have them somewhere else, but that folder appears empty now. I'm curious what happened ...
17
votes
6answers
3k views

Any way to sync directory structure when the files are already on both sides?

I have two drives with the same files, but the directory structure is totally different. Is there any way to 'move' all the files on the destination side so that they match the structure of the ...
14
votes
2answers
970 views

Manipulating X key and pointer grabs on the command line

What command line tools exist to list and manage X server grabs? (That's grab as in key and pointer grabs, i.e. restricting the use of a particular key or mouse button to a particular application, or ...
6
votes
2answers
5k views

How can I rename a lot of files using a regex?

I want to rename a lot of files on Mac OS X (10.7.2).. I don't have the perl package for the rename command. My files have names like "T452-102456-0.png" and I want to delete the "-0" part. I know I ...
6
votes
2answers
9k views

Why is my variable being localized in one 'while read' loop, but not in another seemingly similar loop [duplicate]

Why do I get different values for $x from the snippets below? #!/bin/bash x=1 echo fred>junk ; while read var ; do x=55 ; done <junk echo x=$x # x=55 .. I'd expect this result x=1 cat ...
3
votes
2answers
617 views

What information do I need to solve an APT dependency issue?

I've seen several times people with unmet dependencies, which apt-get doesn't tells straightforward what's the problem, like this one: The following packages have unmet dependencies: ...
35
votes
3answers
5k views

What does size of a directory mean in output of 'ls -l' command?

What does size of a directory mean in output of ls -l command?
6
votes
6answers
2k views

How to clean up file extensions?

I have a directories with .MP3 files which I'd like to change the extensions to .mp3. What's the easiest way to do this? I'm think something along the lines of: find /RootPath -type f -iname "*.mp3" ...
7
votes
3answers
7k views

Automount USB drives with no GUI requirement (halevt replacement)

For minimal installations of Debian, I have been using halevt to enable automounting of USB drives. Halevt is reliable and requires no configuration aside from installing the package. Now, halevt has ...
2
votes
2answers
3k views

Using Awesome window manager on CentOS 7

Awesome works fine on Fedora 19, so it should work on CentOS 7, right? Well, I tried and failed to get it to work. After a long time, I managed to compile it from source and set GDM to boot from an ...
299
votes
7answers
26k views

How can I find the implementations of Linux kernel system calls?

I am trying to understand how a function, say mkdir, works by looking at the kernel source. This is an attempt to understand the kernel internals and navigate between various functions. I know mkdir ...
80
votes
2answers
13k views

Why do we use su - and not just su?

I don't understand why su - is preferred over su to login as root.
53
votes
5answers
39k views

What is a Superblock, Inode, Dentry and a File?

From the article Anatomy of Linux File Systems by Tim Jones, I read that Linux views all the file systems from the perspective of a common set of objects and these objects are superblock, inode, ...
52
votes
6answers
2k views

Resources for portable shell programming

What resources exist for portable shell programming? The ultimate answer is to test on all targeted platforms, but that's rarely practical. The POSIX / Single UNIX specification is a start, but it ...
52
votes
8answers
26k views

How can I move files and view the progress (e.g. with a progress bar)?

When moving large directories using mv, is there a way to view the progress (%)? The cp command on gentoo had a -g switch that showed the progress.
33
votes
2answers
22k views

Do the parent directory's permissions matter when accessing a subdirectory?

If I have a root folder with some restrictive permission, let's say 600, and if the child folders/files have 777 permission will everybody be able to read/write/execute the child file even though the ...
61
votes
9answers
3k views

Remember a half-typed command while I check something

I often find myself in the following position: I've started typing a long command at the bash prompt, but half-way through I find out I need to check something with another command. This is a problem ...
28
votes
4answers
2k views

What are the responsibilities of each Pseudo-Terminal (PTY) component (software, master side, slave side)?

I am trying to figure out how a tty works1 (the work-flow and responsibilities of each elements). I have read several interesting articles about it, but there are still some blurry areas. This is ...
64
votes
6answers
25k views

Can I create a user-specific hosts file to complement /etc/hosts?

Is it possible to add a list of hosts that are only specific to a certain user? Perhaps a user-specific hosts file? This mechanism should also complement the entries in the /etc/hosts file.
52
votes
14answers
81k views

SSH tunneling error: “channel 1: open failed: administratively prohibited: open failed”

When I open this ssh tunnel: ssh -nXNT -p 22 localhost -L 0.0.0.0:8984:remote:8983 I get this error when trying to access the HTTP server running on localhost:8984: channel 1: open failed: ...
31
votes
11answers
22k views

How can I reliably get the operating system's name?

Say I am logged into a remote system, how can I know what it's running? On most modern Linuxes (Linuces?), you have the lsb_release command: $ lsb_release -ic Distributor ID: LinuxMint Codename: ...
16
votes
3answers
4k views

Reattach to lost X11 session

I'm using X11 forwarding over ssh to run Linux apps on my Windows box, and when the network drops it loses everything that was running. Is there anything similar to screen for X11?
28
votes
5answers
6k views

Block network access of a process?

Is it possible to block the (outgoing) network access of a single process?
24
votes
3answers
23k views

Installing Grub 2 on a USB flash drive

MultiBootISOs is a tool that let you install Grub on a USB flash drive. I really like it because it lets me boot from ISO files and let me put a bunch of ISOs on my USB and choose which one to boot. ...
17
votes
3answers
6k 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 ...
10
votes
1answer
4k views

Where should a local executable be placed?

I have an executable for the perforce version control client (p4). I can't place it in /opt/local because I don't have root privileges. Is there a standard location where it needs to be placed under ...
16
votes
4answers
4k views

The merits of a partitionless filesystem

I ran into something a couple of weeks ago that I'd never seen before: A filesystem (ext3 I believe) installed to a storage device without a partition. In essence /dev/sdb was the entire filesystem. I ...
12
votes
1answer
2k views

Can one PC be used by two users at the same time via dual-monitor?

Since modern PCs can use two screens at the same time I wonder if it is possible to plug in two keyboards and mouses as well to have the two screens run two (more or less) independent X-sessions at ...
13
votes
2answers
8k views

Debian based system, only one gui program, nothing else

I would like to make a debian system where you can only open one GUI program at boot, no other graphical interface, no minimize, or any X apart from that program, is there a way to do it on debian if ...
12
votes
8answers
29k views

Changing extension to multiple files

I would like to change file extension from *.txt file to *.text file, tried using the basename command, but I am having trouble on changing more than 1 file, I am getting a basename: too many ...
9
votes
2answers
6k views

ssh port forward to access my home machine from anywhere

http://serverfault.com/questions/303937/how-to-make-freebsd-box-accessible-from-internet I want to understand this whole process of port forwarding. I read so many things but failing to understand ...
8
votes
2answers
3k views

Find filesystem of an unmounted partition from a script

I'm writing a custom automated install using AIF (Arch Installation Framework), and I need to find the filesystem on a partition given a partition. So far I have this: grok_partitions () { local ...
21
votes
1answer
29k views

How can I increase the number of inodes in an ext4 filesystem?

I had a problem (new to me) last week. I have a ext4 (Fedora 15) filesystem. The application that runs on the server suddenly stopped. I couldn't find the problem at first look. df showed 50% ...
9
votes
3answers
15k views

Extracting a regex matched with 'sed' without printing the surrounding characters

To all the 'sed' doctors out there: I have a seemingly trivial 'sed' question to which I have not been able to find a solution. How can you get 'sed' to exctract a regular expression it has matched ...
4
votes
1answer
2k views

Reading a filesystem from a whole disk image

I ran these commands: VBoxManage clonehd d6b9f0a5-98df-48ca-83c8-91a0809ec349 --format RAW Debian.raw sudo dd if=~/.VirtualBox/HardDisks/Debian.raw of=/dev/sda5 When I try to mount the partition, I ...
14
votes
6answers
1k views

How can I cleanly add to $PATH?

I'd like a way to add things to $PATH, system-wide or for an individual user, without potentially adding the same path multiple times. One reason to want to do this is so that additions can be made ...
6
votes
3answers
638 views

Access to original contents of mount point

On my headless NAS I have sdf1 (a flash-card) mounted as / while /home is mounted from lv00 (an LVM volume backed by a software RAID). To be able to access the machine when the RAID fails, I have a ...

15 30 50 per page