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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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 ...
6
votes
1answer
3k 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
3k 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
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2answers
16k 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
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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 ...
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 ...
6
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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
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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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
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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
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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
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2answers
635 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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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
155 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
273 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
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3answers
781 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
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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
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2answers
736 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
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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
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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
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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
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8answers
756 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
423 views

what console command ./ means?

I saw many times console commands like ./redis-server or ./mongo what exactly ./ means?
5
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5answers
382 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?
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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
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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
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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
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5answers
11k 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
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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?
5
votes
3answers
12k views

How do I turn on gzip in Apache2?

I simply did : sudo aptitude install apache2 And that's how my server is set up. No extra modules, no nothing. I'm on ubuntu jaunty.
5
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7answers
14k 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
3answers
3k 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 ...
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. ...
5
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3answers
394 views

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.
5
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4answers
937 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 ...
5
votes
2answers
35k 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, ...
5
votes
2answers
4k views

Nginx to apache reverse proxy, instruct use of unix sockets

My Nginx reverse proxy works on the same machine as the webserver(apache) as follows server { server_name site.net; location / { proxy_pass http://localhost:82; ...
5
votes
5answers
3k views

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 ...
5
votes
3answers
11k views

PYTHONPATH environment variable…how do I make every subdirectory afterwards?

I currently do this: PYTHONPATH=/home/$USER:/home/$USER/respository:/home/$USER/repository/python-stuff How can I make it so that the PYTHONPATH can include everything subdirectory? PYTHONPATH = ...
5
votes
4answers
12k views

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 ...
5
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2answers
1k 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 . ...
5
votes
2answers
683 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 ...
5
votes
4answers
15k 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 ...
5
votes
6answers
318 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 ...
5
votes
2answers
4k 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 ...
5
votes
3answers
903 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 ...
5
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5answers
3k views

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 ...
5
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4answers
7k views

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: ...
5
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2answers
8k views

syslog ip ranges to specific files using `rsyslog`

I have many Cisco / JunOS routers and switches that send logs to my Debian server, which uses rsyslogd. How can I configure rsyslogd to send these router / switch logs to a specific file, based on ...
5
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1answer
25k 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, ...