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

learn more… | top users | synonyms

7
votes
1answer
3k views

nodejs server hanging from time to time

I have a node server (0.6.6) running an Express application, along with Mongoose and s3, on an Ubuntu 11.04 machine. Several times per hour, the server is hanging. That means that the application is ...
7
votes
2answers
24k views

In unix/linux, what is the proc directory for? why does it exists? [closed]

In unix/linux, what is the proc directory for? why does it exists? What can I use it for (if not just for the system)?
7
votes
4answers
3k views

Automatically-reconnecting TCP tunnel

I have an unreliable network connection between two machines: sometimes active TCP connections get dropped for reasons beyond my control. I want to establish a reliable TCP connection between the two ...
6
votes
5answers
3k views

Combine multiple unix commands into one output

I need to search our mail logs for a specific e-mail address. We keep a current file named maillog as well as a week's worth of .bz2 files in the same folder. Currently, I'm running the following ...
6
votes
3answers
235 views

OS/2 grep had a great feature where it would show you n lines BEFORE the search item was found. Is there an equivalent in unix anywhere?

Solaris would be preferable, but I'll take linux or something I can compile. Does such a beast exist?
6
votes
2answers
268 views

Why are Unix applications documented with an number in parenthesis with man?

When I try to get help on a Unix command, I get reference to say tar(1) or lsof(8). Why is there a number within parenthesis and what does it refer to exactly ?
6
votes
6answers
18k views

How do i find out which Fedora version I'm running from the cli (not uname -a)?

I want to know if the box is Fedora Core 4 or Redhat 9, or CentOS, etc... not if it has Kernel 2.6.x
6
votes
6answers
818 views

Source vs Package Managers on the job

I am a bit confused, as there are two ways to install applications. One being to configure and make from source and the other from a package manager. If one were a UNIX/Linux administrator, is it ...
6
votes
3answers
8k views

What's the purpose of setgid directory?

I know how setgid works, but I don't know why it is designed, is there any example to illustrate what problems it solves?
6
votes
5answers
4k views

How to include all files from a directory in shell script (/etc/init.d/iptables in this case)

I have an /etc/init.d/iptables start|stop|restart script on different ubuntu servers (which is a normal shell script) For each new service I have to edit and insert a line to open a port. This leads ...
6
votes
5answers
1k views

Is there still a reason why binding to port < 1024 is only authorized for root on Unix systems?

On Unix systems, binding to tcp port < 1024 from a process without root privileged is denied. What was the initial reason and is it still valid ? For example http server don't need root ...
6
votes
3answers
4k views

How do you tell if a user is “allowed to log in” on Linux?

The question is simple, I want to list all the user accounts which can log in to my system, but I'm not sure if that all the users in /etc/passwd are "could login" users? Details: I can see users ...
6
votes
6answers
8k views

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 ...
6
votes
2answers
38k views

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, ...
6
votes
1answer
4k views

Removing a file whose name is the backslash character

I've somehow created a file called \ in a directory (yes, backslash character). I've tried all sorts of sed, find and grep fu but I just can't delete it! I know I could just delete the directory, but ...
6
votes
2answers
4k views

Encoding to base32 from the shell

I'm looking to encode an input string to base32 encoding directly from the shell. I'm looking to do this in ubuntu, but I imagine flavor doesn't particularly matter here. Are there any existing ...
6
votes
4answers
16k views

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 ...
6
votes
2answers
17k views

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 ...
6
votes
2answers
5k views

Cannot ping over LAN until a ping is received

I have two OSX machines on a local subnet. Pings from Machine A to Machine B consistently timeout until Machine B pings Machine A. After B pings A, A can successfully ping B, but this success is ...
6
votes
2answers
2k views

Start detached screen session

I would like to start screen detached session, but I want to evaluate some bash. It seems screen only supports an executable and binary. I want do do some magic like: screen -d -m script.sh 2>&...
6
votes
8answers
2k views

Using inittab to ensure sshd (and other important items) are still running — any drawbacks?

Having managed to kill sshd on a remote machine (by running a script which used all available memory in the machine, oops...) which I have no access to other than visiting the hosting for[1], I was ...
6
votes
4answers
11k views

how to export VARs from a subshell to a parent shell?

I have a Korn shell script #!/bin/ksh # set the right ENV case $INPUT in abc) export BIN=${ABC_BIN} ;; def) export BIN=${DEF_BIN} ;; *) export BIN=${BASE_BIN} ;; esac # exit 0 <- ...
6
votes
9answers
4k views

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 ...
6
votes
1answer
26k views

Apache: Configure “LogLevel debug” for certain modules only?

I want to debug some authentication & authorization issues on my webserver, particularly with mod_authnz_ldap and other mod_auth* modules. So I set LogLevel debug in the Apache configuration, ...
6
votes
3answers
4k views

UTF-8 and !# shell scripts

Is there a way to configure bash on Linux (red hat and ubuntu) to allow shell scripts to be encoded in UTF-8? I can't find a simple way to change just one little thing and have the whole system just ...
6
votes
1answer
3k views

Using a shell script to check if rsync made any changes

I've got a bash script that rsync's two directories. Sometimes there's a change, odds are there's nothing. I want to run a command only if rsync actually made a change (add/update a file). ...
6
votes
10answers
18k views

Recursive move utility on Unix?

Sometimes I have two trees that used to have the same content, but have grown out of sync (because I moved disks around or whatever). A good example is a tree where I mirror upstream packages from ...
6
votes
2answers
2k views

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 [...
6
votes
2answers
651 views

Freebsd Secondary Group not allowing folder deletion

TLDR: I have a user that is a member to a group as a secondary group. This user can delete files with 664 perms as a secondary user, but not directories with perms of 775. Details: I have a user. ...
6
votes
3answers
2k views

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 ...
6
votes
2answers
157 views

Chrooting a users login

I want to limit certain users on my system to a subset of commands and have absolutely no access to the rest of the system. I figure chrooting is the way to solve this but I only know how to chroot a ...
6
votes
2answers
286 views

Calling sync/fsync slows IO after 30 minutes uptime

After 30 minutes of uptime using Ubuntu 14.04 with an ext4 hybrid SSD I see many processes blocking IO using iotop. The root cause of this slowdown has been traced back to the Unix system call sync. ...
6
votes
3answers
862 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
6
votes
7answers
412 views

*nix measure memory usage

i'd like to measure the total memory (like RAM) used by a program during its execution. Ideally, something like time that runs the program and print stats when it exits. Is there such a standard tool ...
6
votes
2answers
769 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 ...
6
votes
2answers
1k 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 ...
6
votes
4answers
4k views

How to refresh an online website mirror created with `wget --mirror`?

One month ago, I used "wget --mirror" to create a mirror of our public website for temporary use during an upcoming scheduled maintenance window. Our primary website runs HTML, PHP & MySQL, but ...
5
votes
8answers
13k views

Light Weight Virtual Machines / *nix Distributions [closed]

Does anyone maintain a list of Light Weight *nix distributions, ideally just a VM that can be downloaded.
5
votes
8answers
762 views

Identifying changed files on *nix webserver

Looking for some (*nix) software which will build an index of "interesting" files on a server and notify when certain of those files contents are modified, or new files appear. Similar to rkhunter et ...
5
votes
2answers
424 views

what console command ./ means?

I saw many times console commands like ./redis-server or ./mongo what exactly ./ means?
5
votes
5answers
423 views

How to find all filenames with given extension

I need to find all .pem files on my system. Would the following do this? sudo find / -type f -name *.pem If not, how would I write a find command to find every file of the sort?
5
votes
5answers
1k views

Restore old SunOS tapes

I have some old SunOS tapes I need to look at the table of contents before I shred them. Is there a Linux solution to restore these tapes?
5
votes
4answers
5k views

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 ...
5
votes
6answers
369 views

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 ...
5
votes
5answers
12k views

How do I know what processes are using the network?

Sometimes I can see heavy usage of network in my Gnome System Monitor. I wonder what process is downloading/uploading data. Is there any tool which can show me: what processes are using the Internet ...
5
votes
2answers
2k views

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?
5
votes
7answers
15k views

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 ...
5
votes
1answer
3k views

How can I start a shell inside a jail on FreeBSD?

I have access to a a previously set up FreeBSD box with a number of jails on it. One of the jails is an SQL server, and does not have ssh enabled on it. How can I gain access to a shell on that jail ...
5
votes
3answers
2k views

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. ...