Red Hat Enterprise Linux (RHEL) is a commercially supported Linux distribution.

learn more… | top users | synonyms (1)

79
votes
11answers
118k views

Is CentOS exactly the same as RHEL?

I'm sure this question has been asked again and again elsewhere (I did not find anything specific to CentOS vs RHEL in SE), but I would still like to ask and confirm a few specific points. I am well ...
61
votes
7answers
26k views

What is the Linux equivalent to C:\Program Files?

I understand that in Windows as well as Linux and Unix, a program|application|software can be installed in any directory. Also if packages are installed using the distribution's packaging system, it'...
31
votes
3answers
5k views

What is the difference between these commands for bringing down a Linux server?

Reading "What is the difference between Halt and Shutdown commands?" , I generally have an idea what does the command shutdown does, with or without -h/-r options. The "halt" command performs ...
29
votes
6answers
25k views

Open a RPM on a Mac?

I am on a MacBook Pro running Apple Leopard (Mac OS X 10.5.8). I would like to unpackage a RPM and view the files contained within the wget-1.11.4-2.el5_4.1.src.rpm . I don't need to install the ...
29
votes
4answers
25k views

Why SSH takes a long time to Connect

I have noticed that some Linux Servers in Network takes long time to connect using ssh. Situations: There are two situations I have faced: On some servers some times it takes a long time to ask ...
25
votes
5answers
54k views

How to know which Linux and which version I am using

When I run cat /proc/version command in terminal, I got below output: Linux version 2.6.18-348.1.1.0.1.el5 (mockbuild@ca-build56.us.oracle.com) (gcc version 4.1.2 20080704 (Red Hat 4.1.2-54)) #1 SMP ...
23
votes
3answers
2k views

How can I shutdown a RHEL server at 06:45 tomorrow morning?

I just received notification that our site has a power outage tomorrow morning. I am a Windows admin but I have to cover for our Linux admin who's not around until tomorrow evening. I need to ...
23
votes
2answers
19k views

/dev/tcp listen instead of nc listen

With a netcat listener like: nc -l <port> < ~/.bashrc I can grab my .bashrc on a new machine (doesn't have nc or LDAP) with: cat < /dev/tcp/<ip>/<port> > ~/.bashrc My ...
22
votes
3answers
18k views

.bash_profile not sourced when running su

I have a user, say user1, which has modifications to its .bash_profile, one of them changing the PATH, e.g.: export PATH=/some/place:$PATH. This change works fine if I log on as user1 or do a su - ...
22
votes
1answer
34k views

Unable to delete file, even when running as root

I am in the process of migrating a machine from RHEL 4 to 5. Rather than actually do an upgrade we have created a new VM (both machines are in a cloud) and I am in the process of copying across data ...
21
votes
3answers
24k views

Piping from grep to awk not working

I am trying to grep the ongoing tail of file log and get the nth word from a line. Example file: $ cat > test.txt <<EOL Beam goes blah John goes hey Beam goes what? John goes forget it Beam ...
21
votes
3answers
54k views

How can I increase open files limit for all processes?

I can use ulimit but I think that only affects my shell session. I want the limit increased for all processes. This is on Red Hat.
19
votes
4answers
3k views

What makes CentOS “enterprisey” compared to “generic” distributions like Ubuntu?

What makes CentOS "enterprisey" compared to "generic" distributions like Ubuntu? When I say "enterprisey" I actually mean "better for server deployments". Just a general question, because I was ...
18
votes
4answers
109k views

How can we change root password?

If we don't know the root password and don't have root access to the machine, how can we change the root password?
18
votes
8answers
85k views

How to boot Linux to command-line mode instead of GUI?

I am using 32-bit Red Hat Linux in my VM. I want to boot it to command-line mode, not to GUI mode. I know that from there I can switch to GUI mode using startx command. How do I switch back to command-...
18
votes
2answers
63k views

Nslookup: command not found error on RHEL/CentOS 7

During linux installation I selected "minimal" option: When I went to run the nslookup command to look up an IP address I got the error message nslookup: command not found as shown in the example ...
18
votes
3answers
51k views

How to disable SELinux without restart?

I need to disable SELinux but cannot restart the machine i followed this link where i get bellow command setenforce 0 But after running this command i checked for that sestatus SELinux status: ...
17
votes
7answers
7k views

Is there a difference of stability between Linux distros?

I've using Debian since 2010 for some home purposes and it has been stable. Is Debian still a good option if I need a server for heavy network, cpu, disk and memory usage? Last month I listened to ...
17
votes
3answers
19k views

Does RHEL/CentOS execute all cronjob files under /etc/cron.d/*, or just some of them?

This is a Red Hat Enterprise Linux 5 system (RHEL). We manage this system using CFengine. We have several cronjobs which are running twice as often as usual. I checked the cronjobs under /etc/cron.d/ ...
17
votes
4answers
11k views

How can I avoid “Run fsck manually” messages while allowing experimenting with system time changes?

I'm working with a system where we want to allow users to play around with the date and time if they want, and where reboots may happen arbitrarily. This is fine, except for one thing: if there's a ...
15
votes
4answers
7k views

Changing the timestamp of a symlink

I know how to change the timestamp of a regular file: touch -t 201301291810 myfile.txt I was not able to do the same with a symlink. Is it possible? Distro: RHEL 5.8
15
votes
3answers
17k views

how to run new software without updating GLIBC?

I installed Mathematica 9 on an old Red Hat Enterprise Linux AS release 4 system. After the installation, I tried to start Mathematica, but following message came out: /home/wcbao/M/Wolfram/...
14
votes
1answer
3k views

Why does Red Hat Linux use such an old kernel?

Why does RHEL (and its derivatives) use such an old kernel? It uses 2.6.32-xxx, which seems old to me. How do they support newer hardware with that kernel? As far as I know these kind of distributions ...
14
votes
2answers
17k views

( /etc/sysconfig/iptables ) “Manual customization of this file is not recommended.” Why?

Editing this file directly /etc/sysconfig/iptables can save me so much headaches so much time and so on... and yet on the very top of the file it says.. Manual customization of this file is not ...
13
votes
4answers
35k views

can we know the password for the other users if we have root access?

If a person has root access to a particular RHEL machine, will they be able to retrieve the password of the other users?
12
votes
2answers
24k views

Effect of entries in /etc/securetty

By default on RHEL 5.5 I have [deuberger@saleen trunk]$ sudo cat /etc/securetty console vc/1 vc/2 vc/3 vc/4 vc/5 vc/6 vc/7 vc/8 vc/9 vc/10 vc/11 tty1 tty2 tty3 tty4 tty5 tty6 tty7 tty8 tty9 tty10 ...
12
votes
4answers
9k views

What are the dangers of creating a normal user with UID < 500?

What are the dangers of creating a normal user with UID < 500? Assuming the UID's are not duplicates of existing UID's, what could go wrong? This is not something that I want to do, but something ...
12
votes
2answers
27k views

Equivalent of update-grub for RHEL/Fedora/CentOS systems?

In Ubuntu (and I guess in Debian too) there is a system script named update-grub which automatically executes grub-mkconfig -o with the correct path for the grub configuration file. Is there any ...
12
votes
3answers
19k views

Getting the password expire time

Let me preface this with: I do NOT have root access available. I recently got locked out of my account because I did not know the password expiration was getting close, then elapsed. I want to add a ...
11
votes
4answers
7k views

What's the difference between a hard links and copied files?

My understanding is that hard links include a copy of the original file and that I could delete a hard-linked file in one directory, and it would still exist in the other directory. If that's the ...
11
votes
1answer
31k views

How do I install g++ on RHEL6?

This question seems to have been asked here already. My IT department installed the OS so I don't know how to register it properly but I do have root access. Is there a way to get the same packages ...
11
votes
3answers
4k views

What roles do DAC (file permissions), ACL and MAC (SELinux) play in Linux file security?

I need some clarification/confirmation/elaboration on the different roles DAC, ACL and MAC play in Linux file security. After some research from the documentation, this is my understanding of the ...
11
votes
3answers
27k views

How to set global environment variables at boot through a script, and have them available for an application that runs before login?

I have a service that runs at boot, and in that service it calls a bash script in the background that exports some environment variables. The problem I'm having is that those environment variables ...
11
votes
1answer
34k views

Yum Check Available Package Updates

Red Hat docs say: To see which installed packages on your system have updates available, use the following command: yum check-update What command must I run to view all available versions for ...
10
votes
5answers
20k views

List all RPM packages installed from repo “X”

How can I get a list of all of the RPM packages that have been installed on my system from a particular repo (e.g., "epel")?
10
votes
3answers
193k views

How to find path where jdk installed?

I've installed jdk1.7.0.rpm package in RHEL6. Where I do find the path to execute my first java program?
10
votes
2answers
55k views

How to list groups with gid in redhat?

I first listed the groups using : groups I added group using groupadd -g 300 oinstall groupadd –g 500 dba and then when I do groups root bin daemon sys adm disk wheel sfcb I am unable to ...
10
votes
2answers
2k views

Temporarily change time

I need to test aspects of my software that only happen at certain times of the day. Rather than waiting whole days (and getting here at 2:00 AM), I'd like to change the time. But I'd rather not ...
10
votes
2answers
31k views

Where do installed RPMs go?

I download and install packages on my Red Hat Enterprise Linux Server 6 machine using YUM package manager in command-line mode. When I install apk files on my Android phone, they go to /data/app ...
10
votes
2answers
13k views

Installing a package locally to a user - best practices?

I want to install Git locally to a user on a RHEL server (I don't have root access) What would be your cleanest/ most organized way of installing software to a local user account? Installing ...
10
votes
1answer
8k views

Install g++ when having gcc (C only) — RH6

I have a RHEL 6 machine, which came with gcc but without g++. The gcc version is 4.4.4 20100726 (this is what I got from gcc --version). How can I get g++ working? Currently, the shell just returns "...
10
votes
3answers
7k views

How could we allow non-root users to control a system.d service?

With sysvinit, a sudoers entry like this would suffice: %webteam cms051=/sbin/service httpd * This would allow for commands such as: sudo service httpd status sudo service httpd restart Now, ...
10
votes
1answer
4k views

How to stop users from Switching to Root user

I have disabled the root user login from Sshd.conf file so now no one can login using root user even if they know the password SOMEHOW. Now I have 3 users in server ROOT,EMERG and ORACLE. I want to ...
10
votes
1answer
9k views

How do I reduce the size of locale-archive?

I have a need to reduce the size of the locale-archive file on some of my RHEL6 systems. Here is that file on my system: [root@-dev-007 locale]# ls -l total 96800 -rw-r--r--. 1 root root 99158704 ...
9
votes
2answers
62k views

How to clear memory cache in Linux

Is there any command that by using I can clean the cache in RHEL? I used this command: sync; echo 3 > /proc/sys/vm/drop_caches but it didn't work.
9
votes
2answers
8k views

How can I install ncdu on Red Hat?

The answers provided to this question doesn't help. I'ved tried yum install ncdu But I'm getting No package ncdu available
9
votes
2answers
844 views

Why does “man” command disappear?

I find man command disappears on my RHEL7: # man ls bash: man: command not found... # which man /usr/bin/which: no man in (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/usr/local/go/bin:/root/...
9
votes
2answers
4k views

How to prevent fork bomb?

To prevent fork bomb I followed this http://www.linuxhowtos.org/Tips%20and%20Tricks/ulimit.htm ulimit -a reflects the new settings but when I run (as root in bash) :(){ :|:&};: the VM still goes ...
9
votes
2answers
5k views

Difference between txqueuelen and ethtool tx

What's the difference between the txqueuelen setting that can be applied with either: ifconfig eth4 txqueuelen 5000 ip link set eth4 txqueuelen 5000 And the tx ring size setting that can be applied ...
9
votes
2answers
38k views

How can I run a shell script as a daemon under Redhat?

I've got a shell script, which is essentially a one liner with some logging, which I'm trying to run this from an init script. I'm using the daemon function inside of /etc/init.d/functions to run it, ...