Questions tagged [linux]
Linux is the generic term for a UNIX-like open source operating system based on the Linux kernel.
38,548
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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 ...
1
vote
1
answer
125
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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 (...
3
votes
1
answer
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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 ...
8
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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 ...
9
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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 ...
3
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1
answer
3k
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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 ...
0
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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 ...
7
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3
answers
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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 ...
2
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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 ...
9
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4
answers
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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 ...
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4
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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 ...
11
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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 ...
4
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1
answer
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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 ...
1
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1
answer
2k
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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:...
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1
answer
245
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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 ...
7
votes
2
answers
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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?
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1
answer
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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 ...
0
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1
answer
1k
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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, ...
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 ...
1
vote
1
answer
3k
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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 ...
0
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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 ...
2
votes
1
answer
3k
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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 ...
1
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1
answer
142
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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 ...
0
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3
answers
3k
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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 ...
8
votes
1
answer
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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 ...
0
votes
1
answer
3k
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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 ...
0
votes
1
answer
390
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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 ...
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1
answer
767
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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. ...
6
votes
5
answers
6k
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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-...
1
vote
2
answers
801
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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....
2
votes
2
answers
146
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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
...
2
votes
3
answers
2k
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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.
8
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6
answers
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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 ...
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1
answer
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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 ...
0
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1
answer
1k
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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 ...
0
votes
1
answer
41
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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 ...
1
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1
answer
890
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"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 ...
2
votes
1
answer
2k
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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 ...
2
votes
2
answers
146
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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 ...
0
votes
1
answer
1k
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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 ...
1
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1
answer
204
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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 ...
0
votes
2
answers
3k
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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 ...
12
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3
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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 ...
3
votes
1
answer
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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 ...
4
votes
3
answers
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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
...
3
votes
1
answer
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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 ...
7
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5
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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 ...
2
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0
answers
2k
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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 + ...
0
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1
answer
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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 ...
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3
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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,...