Questions tagged [linux]

Linux is the generic term for a UNIX-like open source operating system based on the Linux kernel.

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What happens if a linux kernel argument is passed twice with different values?

As the question states, what if I pass kernel /vmlinuz audit=1 audit=0 Will auditing enabled or disabled? Or will the kernel just freak out? Or is it undefined and will depend on the build of the ...
Flamewires's user avatar
1 vote
1 answer
125 views

Linux server - random connection banning

I'm trying to figure out why this keeps happening. We have one Ubuntu Server in front of our Web stack that receives a good 100s of requests per second. Sometimes, I wont be able to access any site (...
Angelo Vargas's user avatar
3 votes
1 answer
3k views

Beginners Guide to SNMP? [closed]

I have been searching for days on a beginners guide or tutorial on understanding and using SNMP. I am looking for a guide that starts from the very basics of explaining what an OID and MIB's are to ...
user avatar
8 votes
3 answers
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Is there a way to force heartbeat to add new ip addresses to the system without a full restart?

We utilize heartbeat for High Availability. I'd like to add an additional ip address to the heartbeat cluster, but I don't want to do a full restart of the cluster in the process. Is there a signal ...
Peter Grace's user avatar
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9 votes
2 answers
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htop Memory meter is full. I haven't even started any service yet

I don't understand why my htop meter is full already. I'm not even running some task. Here's the screenshot of my htop: The green meter shows used memory, the blue meter shows buffers, the yellow ...
Raymond's user avatar
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3 votes
1 answer
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SSH traffic redirect for LXC containers

I use LXC containers for ssh hosting and I would like to redirect SSH/SFTP traffic (using port 22) to the container's private IP address but on a user/IP basis. That is - one source port, many ...
ahes's user avatar
  • 95
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2 answers
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Can I drop email software if only using external SMTP?

I have a dedicated server hosting 2/3 web apps (web-server + SQL server among other things) on Debian. Now from time to time theses web apps send mails to their respective users using SMTP services ...
jchatard's user avatar
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7 votes
3 answers
4k views

QEMU-KVM Linux virtualization on the command line

I recently discovered that qemu-kvm has a very promising -curses option that, instead of starting an X window, will show a nice ncurses output from the guest suitable for managing a Linux guest from ...
malloc47's user avatar
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2 votes
2 answers
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Load average is 50 while CPU Utilization is %60

We use EC2 Auto Scaling and recently decided to change Instance type from m2.2xlarge to c1.xlarge (High Memory to High CPU) because average amount of used RAM per Instance is 2G, thus we don't need ...
Roman Newaza's user avatar
9 votes
4 answers
32k views

Crontab to restart service

I am running a web server on an AWS EC2 micro instance. The instance has ~630MB of RAM. With time, I have several httpd processes and very little free RAM. When I restart the httpd service, I end up ...
Lord Loh.'s user avatar
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1 vote
4 answers
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How many subdirectories does the XFS filesystem support within a given directory?

EXT3 supports 32,000 subdirectories. EXT4 supports 64,000... I've read about people having millions of subdirectories on the XFS filesystem, but can't find an exact value referenced anywhere. How ...
T. Brian Jones's user avatar
11 votes
10 answers
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How does the number of subdirectories impact drive read / write performance on Linux?

I've got an EXT3 formatted drive on a Linux CentOS server. This is a web app data drive and contains a directory for every user account ( there are 25,000 users ). Each folder contains files that ...
T. Brian Jones's user avatar
4 votes
1 answer
7k views

What does the message, "too many links" mean when using CP on Linux?

I am copying 25,000 folders containing hundreds of files each from one hard drive to another on the same Linux server. The destination folder already contains 25,000 different folders full of their ...
T. Brian Jones's user avatar
1 vote
1 answer
2k views

PCAP to Syslog utility

I am looking for a tool which sniff all the traffic on an interface and produce a syslog like Cisco log in real time. Example : Feb 16 10:19:05 tcp S.S.S.S(6083) -> D.D.D.D(80), 1 packet Feb 16 10:...
Dom's user avatar
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1 vote
1 answer
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How do I make a service depend on another service on different server?

I have some java processes which need to be started by roster: J1 on X --> J2 on Y --> J3 on Z An idea comes to my mind is let J1 start automatically and use Nagios + NRPE to start J2 based ...
quanta's user avatar
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7 votes
2 answers
26k views

What's faster for copying files from one drive to another? [closed]

Running linux. I have two identical drives mounted on the same machine. What is faster CP, MV, or RSYNC? Why is one faster than the other? Are there any faster alternatives?
T. Brian Jones's user avatar
1 vote
1 answer
1k views

Linux dynamic rate limiting/throttling

I'm running a video streaming website with lighttpd using http pseudo-streaming to deliver videos. If the user has a very fast connection, this can use bandwidth quite inefficiently. For example if ...
Cameron Martin's user avatar
0 votes
1 answer
1k views

Make rsync working with compressed target or tar creating no increment files

I need to make a backup on my external hard drive. I looked both at rsync and incremental tar. The problem is that I want my backup to be compressed. With rsync I can only compress the data transfer, ...
damluar's user avatar
  • 101
2 votes
1 answer
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What is "certs" in openssl.conf for?

In the openssl.conf can I e.g. see [ CA_default ] dir = $ENV::KEY_DIR # Where everything is kept certs = $dir # Where the issued certs are kept crl_dir ...
Sandra's user avatar
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1 vote
1 answer
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Creating Custom Fedora/CentOS ISOs

I've been working on creating some custom Linux ISOs and have recently ran into some issues. Originally, I used bootcdwrite along with some scripts for create an ISO of the running config on a Debian ...
Eric's user avatar
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0 votes
1 answer
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DB2 to Oracle Migration

I am migrating a very large and complex database from DB2 to Oracle 11g. Can someone suggest any tools / processes to do this very quickly. My database is about 500 GB and it cannot have downtime ...
Autobyte's user avatar
  • 171
2 votes
1 answer
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Cant set iptables rule for FTPS (pure-ftpd with TLS)

I'm running pure-ftpd with TLS support, everything works fine until enabling iptables. With working iptables I can connect to ftp but can't get file list. The ip_conntrack_ftp module is enabled, and ...
B14D3's user avatar
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1 vote
1 answer
142 views

Monitor a file on linux [duplicate]

Possible Duplicate: File audit in Linux: how to watch directory tree for deletions? Find out which process is changing a file In linux is there a command where it can say who are all the users ...
Rajeev's user avatar
  • 251
0 votes
3 answers
3k views

solaris to linux migration

I am trying to migrate from solaris to linux. What are the hurdles I may face in migrating the file systems, and scripts and files? Is there any changes needs to be done on the sh and ksh scripts? I ...
Balualways's user avatar
8 votes
1 answer
29k views

NTP not syncing, only syncs on service restart

My ubuntu 11.10 server has been sitting there quite happily for the last 3 - 4 months, then suddenly the time started going out of sync by one hour. I'm not sure why, nothing has changed re the ...
Michael Barrett's user avatar
0 votes
1 answer
3k views

llinux - replace subnet mask in ifcfg-eth0 with sed or awk

I have 30 linux servers that I need to change subnetmask. I want to use a simple script or a simple command to change the subnemt mask from 255.255.255.128 to 255.255.255.0 in ifcfg-eth0. can ...
edotan's user avatar
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0 votes
1 answer
390 views

Cron job failing on Ubuntu VPS

I have a newly setup Ubuntu VPS that has logcheck installed. Every hour I am getting a email with the following entries: Feb 15 19:09:01 zeus CRON[4626]: (CRON) error (grandchild #4627 failed with ...
Peter Anderson's user avatar
-1 votes
1 answer
767 views

How to configure DNS to point a subdomain to a server?

I need to setup a dns record to point a subdomain to a server. atm I am using godaddy's dns, and I have an "A" record to point to the main server and I need to point fs.domain.com to another server. ...
Ahoura Ghotbi's user avatar
6 votes
5 answers
6k views

SSH without password

I'm unable to ssh without a password for some reason on a new CentOS box. I've tried following these guides: http://linuxproblem.org/art_9.html http://www.thegeekstuff.com/2008/11/3-steps-to-...
Wild Bill's user avatar
  • 227
1 vote
2 answers
801 views

Most secure settings for user dedicated for SSH Tunnel

Due to security reasons, I have created a user on my remote VPS only to use it for SSH tunneling. My local PC goes in hands of many others which scares me because I need to leave that SSH session open....
user avatar
2 votes
2 answers
146 views

Bash: Execute series of command from history

How can I execute a series of commands from my bash history? For instance if I want to execute the commands numbered 34 to 42 in my bash history, I've tried things like: for n in $(seq 34 42); do ...
Frank Brenner's user avatar
2 votes
3 answers
2k views

how to map Linux (CentOS) drive to Mac (Snow Leopard)?

Anyone know how to map a Linux (CentOS 6.2) drive to a Mac (Snow Leopard)? I have root privileges. The Linux machine is not in a local network, but accessed via the internet.
gkdsp's user avatar
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8 votes
6 answers
13k views

Log through a FIFO, then redirect to a file?

I have an application that must log each transaction. Every log message is flushed because we need to have a record of what occurred leading up to a crash. My colleagues and I were curious about how ...
chrisaycock's user avatar
-4 votes
1 answer
274 views

I still don't understand FC HBAs and such things [closed]

There is NO documentation out there. The companies don't offer any help on their products, and there aren't text books or anything. I want to set up a storage link between my desktop and my file ...
timramich's user avatar
0 votes
1 answer
1k views

Linux oom-killer kills Jboss on Ubuntu Server (hosted Amazon EC2)

We having some trouble with oom-killer and JBoss on Ubuntu Server. What I want to know is if there a way to avoid this with extra parameters passed to the JVM or to JBoss? On the other hand, do you ...
PapelPincel's user avatar
0 votes
1 answer
41 views

Updating remote user's locally installed intranet source

We have remote users who are in and out of connection. They have local databases as well as locally hosted versions of our intranet. From here they fill out workorders. The workorders go into a ...
timlonx's user avatar
1 vote
1 answer
890 views

"AUTHENTICATE_"environment variables missing in Apache + LDAP authentication

According to the Apache 2.2 documentation, after a successful authentication against Active Directory the LDAP attributes specified in the AuthLDAPUrl directive should be available as environment ...
alexandrul's user avatar
  • 1,435
2 votes
1 answer
2k views

How to run easy_install and pip without root, without virtualenv?

People have access to servers as normal users (jailed actually), and they're advised - at the moment - to download whatever python packages they need, setup.py build them, then add their location to ...
Stefano Palazzo's user avatar
2 votes
2 answers
146 views

What is the best structure to save incremental subfolders?

I have 3 different folders containing particular information about sales orders. Everything was working fine but a few days ago I started having an issue about the amount of subdirectories in each of ...
Mauro Morales's user avatar
0 votes
1 answer
1k views

Is there a system wide limit to the total amount of socket & queue buffer space?

in Linux I know that you can tweak the maximum buffer size per socket connection, but is there a system wide limit to the amount of space the buffers can take up and does this apply equally to the ...
Joe's user avatar
  • 101
1 vote
1 answer
204 views

How to verify application up or not?

I would like to write a script to check whethere the application is up or not using unix shell scripts. From googling I found a script wget -O /dev/null -q http://mysite.com, But not sure how this ...
Selvakumar P's user avatar
0 votes
2 answers
3k views

Can I close or disable ports without iptables

I need to disable or close a couple of ports on a RHEL 5.3 Redhat server, without using IPtables .IPtables is already switched off (disabled)on this system.Is there any alternative way of closing or ...
Dominiqs's user avatar
  • 187
12 votes
3 answers
13k views

Tuning Linux disk caching behaviour for maximum throughput

I'm running into a maximum throughput issue here and need some advice on which way to tune my knobs. We're running a 10Gbit fileserver for backup distribution. It's a two disk S-ATA2 setup on an LSI ...
Peter Meyer's user avatar
3 votes
1 answer
3k views

How to combine different pidstat outputs (CPU, I/O, Disk Usage)

I would like to use pidstat to get both -u, -r and -d flags. Is there a way to do so? The idea, is to get both CPU, I/O and disk usage. Cheers Ps. Combining the flags as -urd doesn't work in Ubuntu ...
Emanuele's user avatar
  • 203
4 votes
3 answers
5k views

Loopback interface on Linux catches all loopback traffic

On a linux machine with a normal loopback interface: $ ifconfig lo lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host ...
Matthew Buckett's user avatar
3 votes
1 answer
63 views

Automating enabling and disabling specific services for brief maintenance windows

For short periods of time (generally measured in seconds or minutes), I need to enable ftp (vsftpd) access on a webserver hosting WordPress so that plugins, themes, etc can be updated via the WP ...
warren's user avatar
  • 18.7k
7 votes
5 answers
25k views

How can I redirect a port number on Linux?

I have a Tomcat application running on my Linux machine on port 8080 (www.myapplication.com:8080/myapps). I want to redirect the Tomcat port :8080 to the default HTTP port of :80 so that the ...
user avatar
2 votes
0 answers
2k views

IPSec VPN login failing with certificate authentication

I am working on an IPSec VPN solution allowing iPhones / iPads to connect to a Linux server running Gentoo. I have been able to get the VPN functioning as expected using PSK authentication (PSK + ...
Michael Gorbach's user avatar
0 votes
1 answer
40 views

yum to install fails on default empty server

I used to download Fedora from site X, for example, but lately the site has not updated itself with new packages, therefore commands used to install any of those packages report back with errors as ...
user1125233's user avatar
1 vote
3 answers
681 views

Limiting SSH root logins to only "safe" networks in OpenSSH 4.x

We want to limit root SSH login to only a few networks that we consider "safe" (VPN, etc.) without imposing the same condition on other accounts. In OpenSSH 5.x, we could use the match block. However,...
Belmin Fernandez's user avatar

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