Install rsync in freebsd from source

On the server, i want to install rsync have no ports as it was older version FreeBSD 5.4 and is not supported, so install rsync from source.

After install, you need to run rehash command

See FreeBSD

maximum number of open files and file descriptors in linux

To see open files in linux use the command

There is a limit set in the kernel on how many open file descriptors are allowed on the system. This may be compiled in, or it may be tunable on the fly. In Linux, the value of this parameter can be read from and written to the proc filesystem.

On this system 1,31,072 open file descriptors are permitted. We are unlikely to run out. If we wanted to change it, we’d do something like this:

But how do we know how many file descriptors are being used?

lighttpd too many open files

lighttpd server crashes with fllowing error in error_log file.

As lighttpd is a single-threaded server, its main resource limit is the number of file descriptors, which is set to 1024 by default (on most systems).

If you are running a high-traffic site you might want to increase this limit by setting server.max-fds.

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maximum number of open files and file descriptors in linux

df not showing all mounts

On a server, df not showing all mounts

This is caused by corrupt /etc/mtab

To fix

See df

Show disk usage with df

df command shows patritions and disk used by each partitions.

df not showing all mounts

RHCSA Study Guide

1. Logical volume ‘home’ as created and mounted. Reduce its size to ‘192M’ (size from 185M to 200MB is acceptable)

2. Add a group sysmgrs

Add a user Natasha such that user’s secondary group is sysmgrs.

Add a user harry such that user’s secondary group is sysmgrs.

Add a user sarrah, who has no interactive shell, and not belongs to the group sysmgrs.

Set password of Natasha, harry and sarrah to lotawens.

3. Configure FTP access on your virtual machine to allow permission for anonymous user.

4. Make a collaborative directory /a/b and set the permission as

Group ownership of /a/b is sysmgrs

The directory should be readable, writable and accessable to members of sysmgrs, but not to any other user. ( it is undershould that root has access to all files and
directories on the system)

Files created in /a/b automatically have group ownership set to the group sysmgrs.

5. Copy the file /etc/fstab to /var/tmp. Configure the permissions of /var/tmp/fstab so that,

The file /var/tmp/fstab is owned by the root user

The file /var/tmp/fstab is belongs to group root

The file /var/tmp/fstab is should not be executable by anyone

The user natasha is able to read and write /var/tmp/fstab

The user harry can neigher write not read /var/tmp/fstab

All other users (current or future) have the ability to read /var/tmp/fstab

6. set cronjob for user natasha to do /bin/echo hiya at 14:23

7. shares remote users. Configure ldap such that ldapusers has no home directory until we do automounting.

baseDN: dc=domain70, dc=example, dc=com


Username: ldapuser70

Password: password

8. configure NTP with that of

9. Implement a web server for the site then perform the following steps:


Rename the download file to index.html

Copy this index.html to the Document root of your web server.

DO NOT make any modifications to the content of index.html

10. Install the appropriate Kernel update from The following criteria must also be met:

The updated kernel is the default Kernel when the system is rebooted.

The orginal kernel remains available and bootable on the system.

11. Configure autofs to automount the home directories of ldapusers NFS-exports /rhome to your
machine. ldapuser70’s home directory should be automounted locally beneath /rhome/ldapuser7-. Home directores must be writable by thier users.

User: ldpauser70
Password: password

12. Create a swap partition of 754 MB size. Do not make any change to the existing swap partition

13. Add a user manlo with uid 1353. Set his password as lotawens

14. Locate all files and directories of user jacques and copy it to /root/findfiles

OR locate the files of owner “dax” and copy to the directory /root/founddirectory

OR Find files in your system which is owned by andrew user & save on /backup/somefile.

15. Find all lines contain a string loop in a file /etc/grub.conf copy it to /root/list. Don’t leave a free line in /root/list

16. Create a device:

Logical volume qa with 60 extents.

Volume group qagroup with 16MB extent size.

Mount it permanently under /abc with file system ext3


MySQL ERROR Access denied you need SUPER privilege for this operation

WHen restoring a MySQL database, i get following error

I opened the file in vim editor. On checking line 4382, i found following

This is because some stored procedures use old database user as definer. To fix you need to find and replace all entry for old username with new username.

In vim, i can run

Or delete the DEFINER line from SQL file.

Now restore BACKUP_FILE-modified.sql with

debconf: unable to initialize frontend: Dialog

When installing a program in Ubuntu 18.04 server minimal installation, i get following error

To fix this, run

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Install Unbound DNS caching server

Unbound is an Open source DNS caching and recursive resolver. You can find more about unbound at

To install unbound on Ubuntu/Debian, run

To start unbound

Set unbound to start on boot

To configure your server to use local name servers provided by unbound, edit file


See dns