Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs.

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openwrt: Use rdate with NTP servers?

I've noticed that some embedded devices (such as OpenWRT, which runs on Busybox) use rdate to set the system time, instead of NTP. Rdate is an older time protocol, and I'm having trouble finding any ...
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Does Windows have symlinks?

I have been doing something on Unix that required a symlink. I want to port my application to Windows. Does Windows have symlinks? EDIT: I should be more specific. I'd prefer XP. I'll install Vista ...
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How to create union of two directories?

In case of unix/linux, is there a way to create union of two directories without copying or linking manually everything to a single directory?
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Should I use a login banner and if so, what should it say?

Are interactive login banners worth having? The general consensus is that they are, but what should the banner say? Some things that are being considered (no particular order): ownership of the ...
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How to add a user without knowing the encrypted form of the password?

I use the following command to create a user in a linux machine: useradd -d /home/dummy -g idiots -m -p 12345689 dummy The user is created and the home directory as well. The problem is that I ...
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Why does chmod(1) on the group affect the ACL mask?

I am trying to understand this Unix behavior (which I happen to be testing on Ubuntu 11.10): $ touch foo $ setfacl -m u:nobody:rwx foo $ getfacl foo # file: foo # owner: michael # group: michael ...
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After deleting a large file, how long does it take `df` to pick up the change?

I deleted a 2.3GB log file on my Ubuntu server, and df doesn't seem to be picking up the change. Is there typically a delay before df can detect that a large file has been deleted?
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What equivalent technologies to Microsoft's forthcoming ReFS exist for Linux/Unix?

With the announcement and write-up of ReFS (Resilient File System) on places like arstechnica, I am curious to know what technology, or technology stack, exists for Linux/Unix for a similar outcome. ...
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Is SPF enough to make sure emails get delivered to inbox?

So I just succesfully set up postfix + dovecot. is SPF enough to make sure emails get delivered to my website's users? I don't want my emails to end up in their spam box.
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How to download with wget without following links with parameters

I'm trying to download two sites for inclusion on a CD: http://boinc.berkeley.edu/trac/wiki http://www.boinc-wiki.info The problem I'm having is that these are both wikis. So when downloading with ...
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921 views

Log monitoring toolsets for Unix? [closed]

What are some good tools for monitoring logs on a system? I am currently using logsentry, which basically just runs grep on logs, ignores regexps I tell it to ignore, and mails me everything else, but ...
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Skip over intermediate server via SSH

I just got hired to work in a lab with a big 'ol linux cluster. I'm a mac/windows guy, so I'm still trying to figure out how to navigate around using a 'nix command line. So far I haven't run into any ...
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How do you install ClearCase 7.1 on a Unix-based server with no GUI and no internet?

The challenges set by the ClearCase 7.1 installation process are multiple: The installation for Unix has been changed (no more './install_server' script): a unified GUI-based Java tool is used, both ...
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2answers
967 views

What is the purpose of each of the different UNIX/Linux shell startup files?

Previously, when setting up a *NIX environment for the first time, I would put all of my shell customisations into .bashrc, with the following .bash_profile: if [ -f $HOME/.bashrc ]; then . ...
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2answers
615 views

Shell background processes: what do characters in termination message mean?

I had three background processes, and here's what I've got: [1] Done zcat jan.txt.gz > j [2]- Done zcat feb.txt.gz > f [3]+ Done ...
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How to get the fully qualified name (FQN) on Unix in a bash script?

I have tested hostname on several servers (RedHat, Ubuntu), and hostname -f has proven unreliable, returning sometime the short name only (as described in this question). I can see the fqn in the ...
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In unix, what's the best way to reduce the size of a massive log file that is actively being written to?

On a linux server, I want to reduce the size of a log file which is several GB big. Cutting off the top half, or maybe the first million lines would work.
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execute su -c over ssh

I am trying to check the BIOS version of a server over SSH, a command that requires root privileges: ssh remote-server su -c dmidecode but this of course fails with the error: standard in must ...
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317 views

Web Designer Permissions on a Production Web Server [closed]

Just started working with a small group of front-end web developers who all login to the dedicated WHM/Apache production server with root to modify client web sites. They claim they do not want to ...
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9answers
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How can I test the security of my server?

How can I test the security of my server ? Please I know it is too general question. But I was wondering if there is a tester software or web service checking all ports of your server, or possibly ...
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3answers
857 views

long SSH password vs SSH Keys

Using amazon's EC2 Service, which is awesome in every regard. Only problem is, I have problems logging in with the SSH keys they automatically genarate. I have no idea what the problem is, but have ...
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What's the best way of setting up a cron job to check that a long-running process is still going and if not, start it?

As per the title: What's the best way of setting up a cron job to check that a long-running process is still going and if not, start it? If I start a long-running process in cron, is it going to ...
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2answers
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How to find all ways in which a Unix user account is locked

I occasionally find myself in a situation where an undermaintained system has an account that's been locked out. The problem is that there are a variety of ways in which an account can be locked out, ...
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How do I print contents of at jobs?

I have a Debian box with some jobs scheduled using at. I know I can list the jobs with their times using atq, but is there any way to print out their contents, apart from peeking into ...
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(*nix) Cloud/cluster solutions for scalable web-services

I'm going to build a high-performance web service. It should use a database (or any other storage system), some processing language (either scripting or not), and a web-server daemon. The system ...
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Ganglia without multicast

I'm running Ganglia 3.1.2 on a network where there is no multicast (nor can I turn it on). Does anyone have an elegant solution for getting ganglia to work correctly? I found this: ...
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3answers
132 views

Returning A List Of Quoted Files Paths Using Find

I would like to create a tarball that contains files from a directory that have a ctime of less than 30 days. Most tutorials I have found have basically recommended doing something like this: tar cvf ...
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168 views

Sort Active Processes in Unix

How can i sort active processes by total process time in unix?
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2answers
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UNIX - How to give user rights over another user and so I don't need to sudo or type password?

I have 2 users in question • git user - used for gitosis - so it's a No password user and it can be accessed only through root... • user user - where my files reside so what I would like to do is ...
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How to migrate a web site from one server to another with minimal downtime?

I have a server hosting a web site and other services that needs to be reinstalled. I would like to relocate these services to another server temporarily, with as little downtime as possible. Both ...
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1answer
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Does directory mtime always change when a new file is created inside?

Is it always true that when a new file is created in a directory - the directory's mtime changes?
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5answers
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In UNIX, is it possible to password protect a directory?

Is there a way to password protect a directory in UNIX? Something like: ~$ cd dir ~$ Password: ~/dir$
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Unix/Linux simple log parser (since, until)

Has anyone ever used/created a simple unix/linux log parser that can parse logs like the following: timestamp log_message \n Order the messages, parse the timestamp, and return: All messages ...
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Right aligning text in GNU Screen caption or hardstatusline

I have this in my .screenrc caption always "%{= Kw} [%0c] %-Lw%{= KW}[%50>%n%f* %t]%{= Kw}%+Lw%=| %l | ${FULLHOST}" It normally displays something like this: [01:06] 0$ vim 1$ top 2-$ tail ...
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1answer
880 views

What's the point of using runit in combination with monit?

I see a lot of people using monit in combination with runit. Isn't that redundant? What is the point of using runit as well? Is it because it's more reliable when dealing with services (as it doesn't ...
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What's a proper way of checking if a PID is running?

I have a .pid file, and I need to check if the process is running. So far I found two options kill -0 `cat something.pid` which prints out an error if the pid isn't running. I know this can be ...
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Can I create and manipulate unix “screens” in a script?

I have a work environment on my Ubuntu laptop in which I want to use three different screens. Eg. in terminal, I usually write screen -S mywork run_server_1 then, ctrl-a c to create a second ...
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How to whois microsoft.com from command-line?

If you 'whois microsoft.com', you get a whole bunch of listings from pranksters who thought it would be funny to mess with the listings by putting 'microsoft.com' in their subdomains. The output ...
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How to stay up to date with the latest information about UNIX software patches and upgrades?

Until now I have always used the SecurityFocus mailing lists to keep myself informed about the possible need of upgrading my server packages. The main problems I have with using this method: Massive ...
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963 views

Are ulimits inherited by the shell, by the user, or a combination?

When a process spawns a subshell, how is the ulimit inherited? Is it by user, by shell, or a combination? Specifically, this was found in the context of HP Server Automation jobs failing on some ...
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627 views

Does anyone know a simple way to monitor root process spawn

I want to exec a script when a new root process spawns. (on Linux) How can I simply do that ? Thanks
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1answer
426 views

Send interactive zoning commands to Brocade switch

I have a Brocade FC switch that I'd like to do some zoning on. I have a build file with too many lines to copy-paste into a normal interactive session, and I have ssh set up with pre-shared keys ...
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2answers
610 views

DFS and Access Based Enumeration - Unix devices cannot access it

I'm currently experiencing issues with DFS shares and ABE, enabled on a Windows Server 2008 R2 File Server. Everything works fine with Windows, the problem is with Linux/Unix machines. They aren't ...
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1answer
155 views

Crazy idea: Identify if system is idle when it's a black box

I need to be able to tell if a series of servers have anyone active on them, and if not then to automatically shut them down (turn off the VM). It's not a trivial task, because I have 1000+ server ...
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1answer
947 views

Acessing a mercurial repository on a shared host over SSH

I have a shared hosting account with SSH access. I have set up a virtual Python installation and have copies of the system folders in $HOME: ~/bin, ~/lib ... I have installed mercurial through ...
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Please explain the following o/p of “top” command

Please explain the following line from the "top" command in the bold :- Mem: 1026228k total, 449640k used, 576588k free, 44812k buffers Swap: 1052248k total, 2020k used, 1050228k ...
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663 views

Anacron and fcron, what are the differences?

Anacron is a computer program that performs periodic command scheduling which is traditionally done by cron, but without assuming that the system is running continuously. fcron is another ...
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iptables vs. hardware firewall

I was wondering if anyone could speak to the advantages of a hardware-based firewall vs using iptables directly on a web server. I'm evaluating the cost effectiveness of having a dedicated firewall ...
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How do I set 'max threads per process' ulimit for non-root user?

Ulimit man page suggests -r option will set this but it only appears to be valid for the root user and there is no equivalent for setting it via /etc/security/limits? Any ideas?
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What will prevent a reboot?

I've got a Mac fileserver that isn't acting right (and was acting strangely yesterday as well). I set up an audible ping to it, and sshed into it and, as root, issued the reboot command. It did ...