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2407 votes
7 answers

How do I make a POST request using curl?

How do I make a POST request using cURL's command-line tool?
user avatar
2146 votes
3 answers

Why does Windows think that my wireless keyboard is a toaster?

I've inherited an old PC from my girlfriend's dad and when setting up the printer I got a bit of a surprise: Two questions spring to mind here: Why does Windows think my wireless keyboard is a ...
  • 11.7k
1854 votes
14 answers

How do I scroll in tmux?

How do I scroll with either the keyboard or mouse? The tmux man page indicates one must enter copy-mode to scroll. Is there a way to quickly scroll without manually entering copy-mode?
  • 18.7k
1681 votes
10 answers

How can I sort the output of 'ls' by last modified date?

How can I sort the output of ls by last modified date?
user avatar
1573 votes
6 answers

How do I make a machine "blank screen" for a period of time (as a penalty) if certain noise levels are reached?

My kids (4 and 5) yell a lot when playing games on the computer. I found an effective cure for this. When I hear loud noises, I ssh into the game computer and do: chvt 3; sleep 15; chvt 7 This ...
1310 votes
19 answers

Getting curl to output HTTP status code?

I'm using curl at the command line on Linux to issue HTTP requests. The response bodies are printed to standard out, which is fine, but I can't see from the man page how to get curl to print the ...
  • 13.8k
1158 votes
13 answers

Find out which process is locking a file or folder in Windows

How can I find out which process is locking a file or folder in Windows? For instance, when trying to delete a folder, Windows reports this: The action can't be completed because the folder is ...
  • 20.7k
1057 votes
25 answers

How to tell git which private key to use?

ssh has the -i option to tell which private key file to use when authenticating: -i identity_fileSelects a file from which the identity (private key) for RSA or DSA authentication is read.  The ...
  • 12k
1045 votes
17 answers

How to clear/flush the DNS cache in Google Chrome?

As you probably know Google Chrome has its own internal DNS cache. Is there a way to clear it without having to wait for the time out or close the browser?
  • 10.6k
1002 votes
19 answers

What are the Windows A: and B: drives used for?

In Windows you have a C-drive. Everything labeled beyond that is with the following letter. So your second drive is D, your DVD is E and if you put in a USB stick it becomes F and the following ...
860 votes
3 answers

Transatlantic ping faster than sending a pixel to the screen?

John Carmack tweeted, I can send an IP packet to Europe faster than I can send a pixel to the screen. How f’d up is that? And if this weren’t John Carmack, I’d file it under “the interwebs being ...
803 votes
31 answers

Is there a built-in checksum utility on Windows 7?

Is there a built-in checksum/hash utility on Windows 7?
  • 8,357
742 votes
12 answers

What does 'source' do?

$ whatis source source: nothing appropriate. $ man source No manual entry for source $ source bash: source: filename argument required source: usage: source filename [arguments] It exists, and it is ...
  • 8,078
739 votes
10 answers

How to recursively chmod all directories except files?

How to chmod 755 all directories but not files (recursively)? Inversely, how to chmod only files (recursively) but no directories?
721 votes
8 answers

How can I display the contents of an environment variable from the command prompt in Windows 7?

In Windows 7, when I start the Command prompt, is there any command to display the contents of an environment variable (such as the JAVA_HOME or PATH variables)? I have tried with echo $PATH, echo ...
  • 26.1k
718 votes
14 answers

macOS keeps asking my ssh passphrase since I updated to Sierra

It used to remember the passphrase, but now it's asking it to me each time. I've read that I need to regenerate the public key with this command, which I did: ssh-keygen -y -f id_rsa > ...
  • 7,301
698 votes
5 answers

Why does this PNG image display differently in Chrome & Firefox than in Safari and IE?

Check this image out: On Chrome and Firefox it will show as a pear. Now, try to save it and look at it saved on your desktop. Also, try viewing in Safari or Internet Explorer. It will display as ...
  • 3,709
683 votes
18 answers

How are pseudorandom and truly random numbers different and why does it matter?

I've never quite got this. Just say you write a small program in any language at all which rolls some dice (just using dice as an example). After 600,000 rolls, each number would have been rolled ...
644 votes
19 answers

How to *disable* automatic reboots in Windows 10?

Windows 10 lets you 'schedule' a reboot for later. I want to disable it. Evidently Windows scheduled itself for a reboot last night when I wasn't looking and just closed everything I had been working ...
  • 11.7k
642 votes
12 answers

View list of files in ZIP archive on Linux

How can I view the list of files in a ZIP archive without decompressing it?
  • 6,963
631 votes
5 answers

How can I get the same SSID for multiple access points?

I need to upgrade my existing wireless infrastructure and this time I want 2 access points to cover my house, since I get blind spots no matter what with a single AP. I have physical cabling to my ...
  • 6,717
621 votes
41 answers

How to execute a command whenever a file changes?

I want a quick and simple way to execute a command whenever a file changes. I want something very simple, something I will leave running on a terminal and close it whenever I'm finished working with ...
617 votes
17 answers

How to copy with cp to include hidden files and hidden directories and their contents?

How can I make cp -r copy absolutely all of the files and directories in a directory Requirements: Include hidden files and hidden directories. Be one single command with an flag to include the ...
  • 15.1k
605 votes
14 answers

How do I convert a video to GIF using ffmpeg, with reasonable quality?

I'm converting a video to GIF file with ffmpeg: ffmpeg \ -i input.flv \ -ss 00:00:00.000 \ -pix_fmt rgb24 \ -r 10 \ -s 320x240 \ -t 00:00:10.000 \ output.gif It works great, but output ...
604 votes
10 answers

How to stop an automatic redirect from “http://” to “https://” in Chrome

I had something set up wacky in our DNS setup which is now resolved. The remaining problem is that chrome has cached the incorrect setup. Specifically, when using Chrome is now ...
  • 6,149
600 votes
11 answers

From a quality perspective, what is better: turning volume up in the software, in the OS, or on the speakers?

If music isn't loud enough, how do I get the best quality (even if the difference is in fact so small it's negligible)? By making the music louder in my music player, game or other sound-producing ...
  • 4,367
598 votes
24 answers

How do I reorder tmux windows?

In screen, I can just type C-a :number 0 to move a window to the top of the window list and push all the other windows down one. What's the equivalent command sequence for tmux? I looked at the man ...
  • 6,987
596 votes
8 answers

Permissions on private key in .ssh folder?

I changed my permissions in my .ssh folder and now when I use a piece of software that uses my private key, I have to type my password each time. What should my permissions be on my id_rsa file to ...
user avatar
587 votes
5 answers

How do you reload your .vimrc file without restarting vim?

Can you edit your .vimrc file and reload it without having to restart Vim?
  • 5,981
566 votes
5 answers

How to find a directory on linux?

I have a VPS with Suse Linux 10.3. I've logged in via SSH/putty and am trying to find where my web files are located. Since I'm uploading via FTP in a directory called httpdocs, I assume that this ...
563 votes
13 answers

Windows 7 SP1 Windows Update stuck checking for updates

I installed Windows 7 fresh and installed SP1. Now, when I try to check manually for Windows Updates it just hangs on the Checking for updates screen. I tried running the tools in How do I reset ...
559 votes
9 answers

Using ffmpeg to cut up video

I am using ffmpeg to cut out a section of a large file like this: ffmpeg -i input.wmv -ss 60 -t 60 -acodec copy -vcodec copy output.wmv The -ss part works fine but the -t is ignored. It correctly ...
  • 5,719
554 votes
12 answers

Automatically answer 'Yes' when using apt-get install

Is there a way to make apt-get install automatically choose "yes" upon the Do you want to continue [y/N]? confirmation dialog?
  • 6,517
551 votes
6 answers

Difference between .bashrc and .bash_profile

What's the difference between .bashrc and .bash_profile and which one should I use?
  • 8,913
550 votes
17 answers

When reading a file with `less` or `more`, how can I get the content in colors?

When I read a file in Linux with the command less or more, how can I get the content in colors?
  • 7,969
544 votes
7 answers

What is the "You have new mail" message in Linux/UNIX?

Sometimes, when I log into a box and 'su' to root, I get a cute little message saying I have mail (thank GOD it's not AOL). Where is this mail? What does it contain? Who/What sent it? How important ...
  • 16.2k
544 votes
4 answers

How to turn off word-wrap in less

Short version: How can I make the less utility in Linux not wrap lines? Long version: Often I need to view huge CSV files using less with hundreds of columns. I frequently only care about the first ...
  • 8,932
532 votes
3 answers

"directory junction" vs "directory symbolic link"?

In the context of NTFS: MKLINK [[/D] | [/H] | [/J]] Link Target /D Creates a directory symbolic link. Default is a file symbolic link. /H Creates a hard link instead of a symbolic link. /J ...
  • 26.2k
529 votes
16 answers

Reload a Linux user's group assignments without logging out

When assigning a user's secondary group list using: # usermod -G <grouplist> <user> is it possible to force this group assignment to take effect without logging out all running sessions? ...
  • 5,782
512 votes
12 answers

Create/rename a file/folder that begins with a dot in Windows?

Many programs needs folder names that starts with a dot, like .emacs.d, .gimp-2.2, .jedit etc. How do I create such a folder? When using the Windows Explorer in Windows 2000 (and other versions), I ...
user avatar
510 votes
5 answers

How do I run multiple commands on one line in PowerShell?

In a cmd prompt, you can run two commands on one line like so: ipconfig /release & ipconfig /renew When I run this command in PowerShell, I get: Ampersand not allowed. The `&` operator is ...
  • 8,894
507 votes
9 answers

Did I just get hacked?

I am developing a consumer product, and it is supposed to be connected to the Internet, so as expected, it is connected to the Internet so that I can properly develop it. I went away for an hour or ...
  • 3,519
506 votes
7 answers

How does a computer restart itself?

How can a computer restart itself? After it's off, how does it tell itself to come back on again? What kind of software is it that can do this?
502 votes
14 answers

How do I make rm not give an error if a file doesn't exist?

I'm writing a makefile that will clean up some useless files at the end of the compilation. If a target has already been made, it will of course skip that target and the useless file may not be there....
  • 8,102
500 votes
6 answers

How to decompress a .bz2 file

I have a file as: filename.bz2 I need to decompress. I have tried the command: tar xvjf filename.tar.bz2, but it didn't work as the file is not a tar file. How do I decompress this file?
  • 5,145
498 votes
17 answers

Is there any 'sudo' command for Windows?

I always work on a non-administrator account on my Windows computer. Sometimes I need to install programs which requires administrator access. As I mostly use the Windows command prompt, is there a ...
  • 10.5k
495 votes
9 answers

Can I delete the folder C:\ProgramData\Package Cache\?

There is a new folder full of installers located at C:\ProgramData\Package Cache\. I believe this is from Visual Studio 2012 RC. Can I delete these gigabytes of data without consequences? Are they ...
  • 5,320
482 votes
20 answers

How can I make Chrome stop caching redirects?

I am working on a web application that is using redirects (for pretty URLs). I am trying to debug logic in the way the redirects are working. However Google Chrome keeps remembering the redirects and ...
  • 8,244
482 votes
11 answers

Can I make cURL fail with an exitCode different than 0 if the HTTP status code is not 200?

I was always assuming that when curl got an HTTP 500 response it was returning an exit code that meant failure (!= 0), but that seems to be not the case. Is there a way I can I make cURL fail with an ...
  • 5,085
477 votes
28 answers

How to check if a binary is 32 or 64 bit on Windows?

Is there an easy way to check if a binary is 32 or 64 bit on Windows? I need to check before I move the program to a 32bit machine and experience a spectacular failure.
  • 5,228

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