Databases, Systems & Networks

Source: nixCraft

I am a new Debian Linux v.7.x / Ubuntu Linux LTS user. How do I reinstall a package using apt-get command line?

The Advanced Packaging Tool (APT) works on both Debian / Ubuntu and it can handle the installation and removal of software. You need use apt-get command as follows to forcefully reinstall package. The syntax is:

apt-get --reinstall install PackageNameHere

OR

apt-get --reinstall install Package1 Package2

The --reinstall option re-install packages that are already installed and at the newest version.

Pro tip: Backup configuration files before you reinstall packages. For example, if you are reinstalling nginx web server package, backup /etc/nginx/ with cp command i.e. mkdir /root/nginx.mmddyyyy/; cp -avr /etc/nginx/* /root/nginx.mmddyyy/

Examples

The following command will reinstall rsync package. Open a terminal and then type:
$ sudo apt-get --reinstall install rsync
OR
# apt-get --reinstall install rsync
Sample outputs:

If above method failed for you, try the following syntax. Make sure you backup config file before typing the following commands. Please note that the --purge option is identical to remove except that packages are removed and purged including any configuration files are deleted too.

 
sudo apt-get --purge remove package1
sudo apt-get install package1

Comment rendre la commande ssh-copy-id disponible sur Mac OS X

Si vous avez tenté d’utiliser la commande ssh-copy-id sur Mac OS X, vous avez dû vous rendre compte que, même si openssh est installé nativement, cette commande n’est pas disponible.

Heureusement, cette commande est un simple script qu’il suffit de copier au bon endroit, de lui donner les bons droits et SURPRISE la commande est disponible.

Et comme je suis sympa, eh bien je vous donne tout ça. 😉 Pour commencer le script ssh-copy-id

Ensuite, la méthodologie à suivre pour le mettre en place:

• Télécharger le fichier
• Déplacer le fichier dans le répertoire /usr/bin
• Lui donner les droits nécessaires

$ chmod 755 /usr/bin/ssh-copy-id

Edit

Si vous utilisez homebrew, il existe un package pour faire la même chose :
brew install ssh-copy-id

Source: Mikael Randy

Source: nixCraft

How can I mount remote directory with ssh on a Linux bases system? How do I use SSHFS to mount remote file systems over SSH on a Ubuntu or Debian/RHEL/CentOS/Arch Linux system?

SSH is a secure protocol and you can use it to mount a directory on a remote server or local laptop with the help of the SSHF service. With SSHFS you can mount remote server file system to your local

More on SSHFS

sshfs is a filesystem based on the SSH file transfer protocol. It is used on a client system i.e. you need to install sshfs package on your local computer/laptop powered by CentOS/RHEL/Ubuntu/Debian/Arch Linux. No need to install anything on server (server1.cyberciti.biz). You only need an openssh server installed on server side. Our sample setup:

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Source: nixCraft

How to execute script on the last day of a month on Linux or Unix bash shell? How do I run a disk usage or custom reporting shell/perl/python script on the last day of a month on a Linux or Unix-like systems?

You need to use the date command to find out whether tomorrow is the first day of the next month. If it is true, you can run your script.

Say hello to TZ variable

TZ is time zone environment variable on Linux or Unix-like systems. The TZ environment variable tells functions such as the ctime(3) family and programs like date what the time zone and daylight saving rule is. For example, Greenwich Mean Time can be defined as follows:

TZ='GMT'

You can set TZ as follows to get tomorrow from the current date (+%d):
TZ=GMT-24 date +%d

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Source: nixCraft

I’m running a process to complete backup and covert images in Mac OS X laptop. I do not wish to disable sleep manually from my OS X power options (Energy Saver). How do I temporarily prevent a Mac from sleeping while my process is still active in Mac OS X Unix operating systems? How can I prevent the system from sleeping temporarily from the command prompt?

You can use the caffeinate command. This command creates assertions to alter system sleep behavior. If no assertion flags are specified, caffeinate creates an assertion to prevent idle sleep.

Another option is to use the pmset command to manipulate power management settings.

Syntax

The syntax is:

caffeinate
caffeinate [options]
caffeinate [options] command

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