Top new questions this week:

why is rm allowed to delete a file under ownership of a different user?

From the post Why can rm remove read-only files? I understand that rm just needs write permission on directory to remove the file. But I find it hard to digest the behaviour where we can easily delete ...

/ files / permissions / rm / history / architecture

asked by mtk 40 votes answered by Celada 80 votes

Why does [A-Z] match lowercase letters in bash?

In all shells I am aware of, rm [A-Z]* removes all files that start with an uppercase letter, but with bash this removes all files that start with a letter. As this problem exists on Linux and ...

/ bash / shell / wildcards / locale

asked by schily 21 votes answered by chaos 33 votes

Surprised by behavior of cp with hardlinks

I understand the notion of hardlinks very well, and have read the man pages for basic tools like cp --- and even the recent POSIX specs --- a number of times. Still I was surprised to observe the ...

/ cp / hard-link

asked by dubiousjim 16 votes answered by Celada 17 votes

Correct capitalization of "cron"

I'm not quite sure what the standard is for spelling cron. Does one capitalize the whole word? Just the "C"? All lowercase? Is there even a standard, or do you just spell it in whatever way looks or ...

/ cron

asked by Grayda 14 votes answered by Mark Plotnick 21 votes

What does CTRL+4 (and CTRL+\) do in bash?

I just found out by accident that CTRL + 4 closes programs reading stdin input from the command-line. This is how it looks when I type CTRL + 4 or CTRL + / into programs reading stdin ryvnf:~$ ...

/ shell / command-line / terminal / input / special-characters

asked by ryvnf 14 votes answered by Gilles 23 votes

What system call is used to load libraries in Linux?

In strace outputs, the paths to the libraries that executables call are in calls to open(). Is this the system call used by executables that are dynamically linked? What about dlopen()? open() isn't a ...

/ dynamic-linking / shared-library / strace / dynamic-loading

asked by Melab 13 votes answered by Celada 24 votes

bash loop with 0.02 increment

I want to make a for loop in bash with 0.02 as increments I tried for ((i=4.00;i<5.42;i+=0.02)) do commands done but it didn't work. I appreciate if you help me out.

/ bash / for / floating-point

asked by Mehrshad 8 votes answered by roaima 17 votes

Greatest hits from previous weeks:

Why do I need a tty to run sudo if I can sudo without a password?

I have configured sudo to run without a password, but when I try to ssh 'sudo Foo", I still get sudo: sorry, you must have a tty to run sudo. Why does this happen and how can I work around it?

/ linux / bash / ssh / sudo

asked by merlin2011 73 votes answered by Stéphane Chazelas 107 votes

How can I run ssh-add automatically, without password prompt?

I want to communicate between several computers on my network (static ethernet), through ssh. In order to do that I need to run ssh-add every time I login on specific machine, how can I do it so that ...

/ ssh / ssh-agent

asked by zdun8 50 votes answered by Thomas Nyman 80 votes

Can you answer these?

How to force Debian to use a newer version of OpenSSL?

Today I installed ,,empty'' (just minimal set of packages) Debian 8.1 on my VirtualBox. I wanted to play with compiling apps from sources. I started with OpenSSL: compiled from sources OpenSSL ...

/ debian / compiling / openssl / openssh / shared-library

asked by jacek.ciach 1 vote

NUL entry in syslog?

My servers went down on the 30th. It just came back online today. At first I thought it was the router because the router the server is connected to is a bit squirrely but when I checked syslog I have ...

/ linux / syslog / crash

asked by Scoopta 2 votes

Giving a user access to the webcam

I have a user that I use to run untrusted programs (more specifically, Skype). I would like to give that user access to the webcam. I am using Debian, where the standard way to do this is to put ...

/ debian / security / camera / policykit / consolekit

asked by a3nm 2 votes