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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what is the difference between linux and solaris OS?

What is the basic difference between Linux and Solaris? As both the OS are derived from UNIX so where lies the difference between Linux and Solaris? Are they because of creation by different ...
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1answer
298 views

Linux/Unix - /etc/sudoers - host definition

can anybody tell me in which case the sudo host definition is useful? I mean this part of a line in the sudoers file: bob host1 = NOPASSWD: reboot In which environment (except sudo via LDAP) do I ...
7
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2answers
909 views

Custom error message for sshd

Is it possible to set a custom error message for users denied to access a server? In fact, I'd like to only display this message if a user was rejected due to IP filter set in sshd_config. But one ...
7
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5answers
2k views

Replacement for NIS/YP

The company that I am working for is embarking on replacing the current locally developed NIS/YP structure with LDAP. We already have AD in house for the Windows stuff and would like to consider ...
7
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1answer
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using temporary files vs pipes advantages and disadvantages

Say I have a file named jobs.csv and I would like to get the top 50k jobs done by Foo I can either do: # cat jobs.csv | sort -u | head -n 50000 > /tmp/jobs.csv # cat /tmp/jobs.csv | while read ...
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4answers
2k 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 ...
7
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2answers
18k 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)?
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8answers
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Linux - use “su -” but keep the current directory

When I do su - to get to root, my current directory is set to root's home. Is there anyway to keep the current directory that I was in, much like sudo -s. Or is the answer to use sudo?
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5answers
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What are the benefits of the Logical Volume Manager

What are the features and potential benefits of Logical Volume Manager beyond what is detailed on its Wikipedia page?
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3answers
233 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?
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2answers
254 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 ?
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5answers
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How can I manually run a nagios check from the command line?

When defining and testing new services in nagios I have been restarting nagios, then clicking the service, and rescheduling a check for as soon as possible, then waiting until the check happens. Is ...
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3answers
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Non-recursive find on linux

I am trying to find all directories that are directly inside the current directory and older than a specific age. The trick is, I only want to consider the age of the immediate descendants of the ...
6
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6answers
641 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
3k views

Directory that a user can read, but root can't?

There's a directory underneath my homedir called ".gvfs". As my regular user account, I can read it just fine: ~ $ ls -lart ~raldi/.gvfs total 4 dr-x------ 2 raldi raldi 0 2009-05-25 22:17 . ...
6
votes
3answers
5k views

apt-get update/upgrade list without changing anything

I would like to view what packages are available for update/upgrade without actually changing any files becuase there are some packages I wouldn't like to update. Would it then be possible to apt-get ...
6
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3answers
7k views

How can I rename an unix user?

I have a user named hedgehog and I want him to be named squirrel, but I don't want to change his numeric user ID. How can I accomplish this?
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5answers
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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 ...
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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
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5answers
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Command line SIP dialer

Is there a simple command line SIP dialer for unix which can connect to SIP server, make a call and play some media file (wav/mp3)? In ideal I would look like this: sip-dailer +1xxxxxxxxxx ...
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4answers
2k views

Faking the date for a specific shell session

I'm certainly trying to achieve something weird here, but I want to fake the date locally for a shell session on GNU/Linux. I need to black-box test how a program behaves at different dates, and ...
6
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2answers
1k views

Why can the root user edit read-only files, but a regular user with sudo access can't?

If you try to append to a file with no write permissions (say, the /etc/sudoers file which is is owned by root and has 0440 permissions), if you're the actual root user, this works. However, if you're ...
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6answers
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How to check what port mysql is running on

On my windows dev box mysql is running on port 3306 How can I check what port it is running on the unix server that I have to upload the app to.
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2answers
1k 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 ...
6
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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 ...
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2answers
2k views

Copy directory tree without empty directories?

I have the following tree # upper letters = directory # lower letters = files A |-- B |-- C |-- D |-- e <= file |-- F |-- G I need to copy this tree to another destination, ...
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3answers
3k 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
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3answers
3k views

List supported terminal types?

Is there a portable way to list supported terminal types on all *N*X systems? If not, what's the best way to get this list on Solaris?
6
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2answers
5k views

Mount a tar file - not possible?

It seems one cannot mount a tar file (read only), similarly as one mounts an ISO image file. At least, I have not found any implementation. It would be useful, for example to run a find command ...
6
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1answer
1k views

Can i call pushd/popd and prevent it printing the stack?

After calling pushd/popd in bash, it will print off the current directory stack. Is there any way to prevent this behaviour, so that it will act 'quitely'? This sort of noise in a command is uncommon ...
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10answers
17k 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
536 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
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2answers
153 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 ...
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2answers
200 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. ...
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2answers
2k views

Monolithic vs Micro kernel

What are the differences between a monolithic kernel and a microkernel with respect to structure and security. My friend told me that Linux systems have monolithic kernel and thus are not easier to ...
6
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7answers
407 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
2k views

Call to daemon in a /etc/init.d script is blocking, not running in background

I have a Perl script that I want to daemonize. Basically this perl script will read a directory every 30 seconds, read the files that it finds and then process the data. To keep it simple here ...
6
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1answer
2k 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 ...
6
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4answers
3k 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 ...
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9answers
9k views

Bash snippet to move all files in a directory into that directory

I have a directory with lots of files and directories in it. In order to tidy it up, I'm going to put all those files into a directory, so I was going to do something like this: $ ls | wc -l 123 $ ...
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8answers
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Is it possible to prevent SCP while still allowing SSH access?

Using Solaris and Linux servers and OpenSSH, is it possible to prevent users from copying files using "scp" while still allowing shell access with "ssh"? I realize that 'ssh $server "cat file" ' type ...
5
votes
8answers
714 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
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2answers
412 views

what console command ./ means?

I saw many times console commands like ./redis-server or ./mongo what exactly ./ means?
5
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10answers
4k views

Scripting alternatives to Bash shell scripts

I have just migrated to a UNIX workstation. My memory of Bash shell scripts has faded since school and I find the syntax to be highly confusing. I am wondering what other scripting languages are ...
5
votes
5answers
287 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
4answers
4k 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
368 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 ...
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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?
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7answers
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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 ...