A family of Unix-like operating systems using the Linux kernel. If your question is about a certain distribution only, use a more specific tag.

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1answer
51k views

What is the difference between grep, pgrep, egrep, fgrep?

I'd like a walk through on the differences between grep, pgrep, egrep, and fgrep and how I would use them.
31
votes
5answers
4k views

Does running commands verbosely make them slower?

I've found myself using the -v flag for lots of applications less and less (especially for trivial stuff like tar and cp). However, when I did and I was, say, unzipping a large file, it would take ...
31
votes
3answers
72k views

How to check if I have sudo access?

I recently got into trouble because of this. $sudo vim /etc/motd [sudo] password for bruce: bruce is not in the sudoers file. This incident will be reported. Is there a way to check if I have ...
31
votes
10answers
41k views

How to extract text with OCR from a PDF on Linux?

How do I extract text from a PDF that wasn't built with an index? It's all text, but I can't search or select anything. I'm running Kubuntu, and Okular doesn't have this feature.
31
votes
1answer
33k views

How can I logout an open, remote SSH session?

I sshed into a Linux machine (bash shell) from a public Windows machine (in our lab) and forgot to log out. I'm now back at my seat in another room and I am too lazy to walk back and log out that ...
31
votes
3answers
19k views

What is the difference between 'locate' and 'find' in Linux?

Why there are two so similar command in Linux? and normally what are the circumstances to use each of them?
31
votes
8answers
33k views

How to know which Linux Distribution I'm using?

How to know which Linux Distribution I'm using? uname -a gives Linux xxxxxx.net 2.6.9-42.0.3.EL.wh1smp #1 SMP Fri Aug 14 15:48:17 MDT 2009 i686 i686 i386 GNU/Linux How can I know this is ...
31
votes
5answers
17k views

How do I physically find a wifi device using a laptop or mobile phone

Okay, so I have lost my tablet somewhere in my flat and have been searching for hours already. It is an Android device, which seems to have wifi enabled (responds to pings), but doesn't seem to react ...
30
votes
5answers
3k views

Deleting millions of files

I had a dir fill up with millions of gif images. Too many for rm command. I have been trying the find command like this: find . -name "*.gif" -print0 | xargs -0 rm Problem is, it bogs down my ...
30
votes
4answers
20k views

Looping Through Subdirectories and Running a Command in Each

I have a set of repositories sorted into directories based on their VCS (Git, Mercurial, SVN). With Subversion I was able to run svn update * in the parent directory and it would loop through each ...
30
votes
6answers
13k views

/usr/local or /opt?

How do you generally proceed for your package installations on Linux, for packages that are not part of your distrib's repos? On my side I am used to install in /opt. But since, I saw this doc on the ...
30
votes
4answers
37k views

How do I do a binary diff on two identically sized files under Linux?

I have two identically sized files, and I need to do a binary diff to check whether they're the same. I'm currently runnnig diff file1.img file2.img but it's taking quite a while to process my ...
30
votes
4answers
3k views

How to use a Linux system as a land phone

I have a land line connection. I would like to receive and make calls using my computer. It is a basic land line connection which also provides broadband internet. I am not asking about VoIP. I ...
30
votes
7answers
41k views

Batch-convert files for encoding

How can I batch-convert files in a directory for their encoding (e.g. ANSI->UTF-8) with a command or tool? For single files an editor helps, but how to do the mass files job?
30
votes
6answers
23k views

On Linux/Unix, does .tar.gz versus .zip matter?

Cross-platform programs are sometimes distributed as .tar.gz for the Unix version and .zip for the Windows version. This makes sense when the contents of each must be different. If, however, the ...
30
votes
4answers
11k views

bash watch command with colors preserved

From man watch: Non-printing characters are stripped from program output. Use "cat -v" as part of the command pipeline if you want to see them. So how do I use cat -v if I want to see the ...
30
votes
5answers
205k views

How can I resolve the error “cannot execute binary file”?

When I login using SSH, all I can see is this... -bash: /usr/bin/id: cannot execute binary file -bash: [: : integer expression expected I couldn't do anything in here. Commands such as halt, ...
30
votes
2answers
99k views

Creating ext4 partition from console

I have a volume /dev/sda1 (1.2 TB) containing an NTFS partition using 0.6 TB space. I want to make an ext4 partition in the remaining 0.6 TB space. I have not tried anything yet because I don't want ...
30
votes
3answers
25k views

How do I create a relative symbolic link in Linux?

I need a symlink that resolves relative to the directory it is placed in. What command is used to create such a thing?
30
votes
1answer
19k views

Remove single file from zip archive on Linux

I have a zip archive (created automatically in a script with -j -r flags) and I would like to remove a single file from it. I tried as documented. zip -d "picture_43_9.jpg" gallery.zip but I get ...
30
votes
2answers
14k views

How to run a minimal Linux inside a running 64-bit Windows 7

On my previous Windows Vista laptop, I used to run Portable Ubuntu Remix for Windows, which is based on coLinux, like the similar andLinux. This worked fairly well with limited system resources (a ...
30
votes
6answers
16k views

Triple (3) Monitors under Linux

I have a 3 monitor setup (each 1680x1050) via an Nvidia NVS440 (2 GPUs, 2 outputs per GPU totalling 4 outputs); this works fine under Windows XP,7 but caused considerable headaches under Linux (Ubuntu ...
29
votes
4answers
4k views

Windows vs Linux Local Time?

Ever since I started using Linux in dualboot with Windows I noticed that when I rebooted the machine, the time on the other OS was wrong, e.g. it was 12:00 on Linux, then I rebooted and on Windows it ...
29
votes
9answers
79k views

How to convert Word (doc) to PDF in linux?

I have a set of files in .doc format, that need to be converted to .pdf format. I am using Ubuntu linux.
29
votes
3answers
46k views

How to show output on terminal and save to a file at the same time?

I am using: user@unknown:~$ sudo command -option > log to save the results of "command" to the file "log", but I'd like to also get the result on the terminal, is this possible? I am using ...
29
votes
3answers
33k views

Get home directory by username

I want to obtain home dir of any user with echo echo ~puchuu >> /home/puchuu But I cant use variable echo ~$USER >> ~puchuu echo `echo ~$USER` >> ~puchuu
29
votes
5answers
12k views

Sudo vs root; any actual differences?

I'm working with a support member for a product, and he insists that I need to be root to install a series of patches, and that sudo won't work; he doesn't provide a reason but seems very firm in his ...
29
votes
4answers
33k views

How do you find the parent process of a zombie process?

How do you find the parent process of zombie processes? When the child process is something where the parent is not entirely obvious... Is there some way to list processes in tree format or ...
29
votes
3answers
31k views

Why is the CPU usage reported by top in Linux over 100%?

I've seen the CPU usage go over 100%. How is this possible? Is it because I have four CPU cores, so 100% isn't really the max? Also, when a program does this, what else can I do in top besides using ...
29
votes
2answers
32k views

Can GNU Grep output a selected group?

Is it possible to use GNU grep to get a matched group from an expression? Example: echo "foo 'bar'" | grep -oE "'([^']+)'" Which would output "'bar'". But I would like to get just "bar", without ...
29
votes
8answers
10k views

Booting Linux off USB pendrives

Booting a Linux system off USB Pendrives is one of my favorite things. On a laptop we have the following advantages, The Harddisk can be shutdown and that reduces power consumption (hdparm) The ...
29
votes
4answers
33k views

How to retrieve video file information from command line under Linux

I'd like to see from command line all informations pertaining to a given video file, including length, quality, bitrate, resolution, audio and video formats, number and language of audio streams and ...
29
votes
2answers
12k views

Linux: Is there something similar to “top” for I/O?

My disk often is utilized, but top (and htop, a custom replacement) show nothing suspicious. Is there a way to sort processes by I/O (more specific: disk) utilization? EDIT Found out using iotop ...
28
votes
4answers
50k views

How to type special characters in Linux?

In windows there is possibility to type from keyboard special signs by holding alt key and typing a few numbers, that depends on with sign you want to use. Does it work with linux in the same way?
28
votes
5answers
30k views

How Do I Find The Hardware Block Read Size for My Hard Drive?

I'm trying to figure out the optimal size for a large copy from my hard drive using dd. I'm trying to figure out what the best blocksize to use it, which I would assume is the hardware block size for ...
28
votes
4answers
45k views

Delete matching files in all subdirectories

How can I remove all .swp files in all of my subdirectories under Linux?
28
votes
6answers
24k views

How many cores I am using on a Linux Server?

I am just wondering how I can find out in bash how many CPU cores a user is now using on a Linux Server? I am submitting a fair amount of background jobs to the server, so I'd like to write a bash ...
28
votes
4answers
30k views

How can I install objdump on Mac OS X?

I want to get the source code of a small command line tool using objdump on Mac OS X. I've used arm-linux-objdump on Linux and find it a great tool. Is there any way to install objdump on OS X? I've ...
28
votes
5answers
104k views

How can I add a regular user to the sudoers file?

How can I add more users to the "sudoers" file?
28
votes
2answers
67k views

What does /dev/sda for linux mean?

What does : /dev/sda stand for? What does it mean? I have both Fedora and Ubuntu installed and if I explore them using Ext2explore from windows, I see these names : /dev/sda6 /dev/sda9 Please ...
28
votes
9answers
49k views

Flow chart software for Linux? [closed]

Been using Visio at work to do flowcharts, and I'm liking how easy it is to do overall, notably creating and linking shapes. I'm trying to find something for Linux that works the same way, or at ...
28
votes
3answers
55k views

Get Last Modified Date of File in Linux

I'm new to Linux. I'm using the command-line. I'm trying to view the last modified date of a file. How do I do that in Linux from the Command Line?
28
votes
4answers
23k views

How to copy symlinks to target as normal folders

i have a folder with symlinks: marek@marek$ ls -al /usr/share/solr/ razem 36 drwxr-xr-x 5 root root 4096 2010-11-30 08:25 . drwxr-xr-x 358 root root 12288 2010-11-26 12:25 .. drwxr-xr-x 3 root ...
28
votes
2answers
59k views

Allow specific user permission to read/write my folder

I have a folder /home/samantha/folder that I want to share with the user tom. He can read/write the folder. How do I do that? chown wouldn't do it because I still want to be able to be the owner of ...
28
votes
8answers
13k views

faster way to mount a remote file system than sshfs?

I have been using sshfs to work remotely, but it is really slow and annoying, particularly when I use eclipse on it. Is there any faster way to mount the remote file system locally? My no.1 priority ...
28
votes
1answer
38k views

How to use X11 forwarding with PuTTY

I have a VM with RHEL 5 without an X server. My host has Windows 7. I need to connect to the VM and redirect the X11 output of the commands to my host. I know that if my host were a GNU/Linux ...
27
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16answers
74k views

How do I check whether I am using KDE or Gnome?

or maybe something else? I am using Redhat OS.
27
votes
3answers
4k views

How accurate is `md5sum`?

When using md5sum to verify the integrity of a file, how accurate is the process? Does a verified MD5 mean that EVERY bit is exactly the same, or is there a threshold that must be broken before ...
27
votes
4answers
89k views

How to gzip multiple files into one gz file?

I have 100 files: cvd1.txt cvd2.txt ... cvd100.txt How to gzip 100 files into one .gz file so that after I gunzip it, I should have cvd1.txt, cvd2.txt ... cvd100.txt separately? Thanks for your ...
27
votes
7answers
76k views

Copy directory contents using 'cp' command

How do you copy all the contents of one directory into another? For example: $ cd /home/newuser $ cp -a /backup/olduser/* . The problem with the above is that the globing pattern '*' matches the ...