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Articles taggués ‘commandes’

Get Weather Reports from the Command Line with finger

27/03/2019 Comments off
weather-forecast-command-line-finger-graph-no2-610x433

weather-forecast-command-line-finger-graph

 

Checking weather: purpose of the command

There’s no shortage of methods to retrieve a weather report, the web is full of weather resources, everyones iPhone, Apple Watch, and smartphone has a weather app, Siri can tell you the weather, and you can even get the current weather in the menu bar of OS X or from Spotlight on the Mac too.

But for command line users, none of those options are particularly ideal, since it means leaving the command line and the task at hand.

Thanks to an interesting usage of the finger utility, you can quickly retrieve a weather report and weather forecast for virtually any city in the world, right from the command line.

With this trick you’ll see the temperature forecast (in celsius) for the day, wind direction and wind speed, precipitation and precipitation type (rain, showers, sleet, snow, etc), depth of precipitation, and more. This works with any command line that has the finger tool, whether you’re in Mac OS X, linux, BSD, Windows, it doesn’t matter, it will work the same.

To try this out yourself on the Mac, launch the OS X Terminal found in /Applications/Utilities/ and type the following command syntax:

finger (city name)@graph.no

For example, to get the weather forecast for Montreal Canada, you would use the following syntax at the command line:

finger montreal@graph.no

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Categories: Système Tags: ,

How to Run Cron Every 5 Minutes, Seconds, Hours, Days, Months

16/03/2019 Comments off

Source: thegeekstuff.com

Question: How do I execute certain shell script at a specific intervals in Linux using cron job? Provide examples using different time periods.

Answer: Crontab can be used to schedule a job that runs on certain internal. The example here show how to execute a backup.sh shell script using different intervals.

Also, don’t forget to read our previous crontab article that contains 15 practical examples, and also explains about @monthly, @daily, .. tags that you can use in your crontab.

1. Execute a cron job every 5 Minutes

The first field is for Minutes. If you specify * in this field, it runs every minutes. If you specify */5 in the 1st field, it runs every 5 minutes as shown below.

*/5 * * * * /home/ramesh/backup.sh

Note: In the same way, use */10 for every 10 minutes, */15 for every 15 minutes, */30 for every 30 minutes, etc.

2. Execute a cron job every 5 Hours

The second field is for hours. If you specify * in this field, it runs every hour. If you specify */5 in the 2nd field, it runs every 5 hours as shown below.

0 */5 * * * /home/ramesh/backup.sh

Note: In the same way, use */2 for every 2 hours, */3 for every 3 hours, */4 for every 4 hours, etc.

3. Execute a job every 5 Seconds

Cron job cannot be used to schedule a job in seconds interval. i.e You cannot schedule a cron job to run every 5 seconds. The alternative is to write a shell script that uses ‘sleep 5′ command in it.

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Categories: Système Tags: , , ,

Using Bash Arrays with Examples

13/03/2019 Comments off

bash-scripting-32-638Arrays can be a useful tool when coding your bash scripts.  The simplest way that I can define an array is to state that an array is a variable for a multi-instance dataset.

For example, a variable is used when there is a single value from a dataset like the IP Address of a server.  However, an array can be used to store all of the IP Addresses in your server room.

Speaking of IP Addresses and bash arrays, my last article (Detect and Block WordPress Brute Force Login Attacks) includes a script which is an example of how an array can be used in bash scripting.

Because arrays can be so useful in bash scripting, I thought that I would put together the following article detailing ways of Using Bash Arrays with Examples.

Initializing Bash Arrays or Assigning Values to Arrays

For arrays to be useful, we need to be able to assign values to them.  We assign values to an array by listing the array along with its instance number as shown below.  This method will assign each instance of the array one by one.

#!/bin/bash
myarray[0]=Hello
myarray[1]=World,
myarray[3]=Happy
myarray[4]=Friday

# Display all instances of the array
echo ${myarray[*]}

We can see above that in addition to being able to assign the values one by one, we can reference all array instances with an asterisk (*).  Another way to display all instances of the array is to use the following “echo ${myarray[@]}”

We run the script and get:

$ ./arrays.sh
Hello World, Happy Friday

We can also retrieve individual instances of an array by specifying the individual array instance number.  We modify the above script slightly to retrieve a couple of the instances.

#!/bin/bash
myarray[0]=Hello
myarray[1]=World,
myarray[3]=Happy
myarray[4]=Friday

# Display all instances of the array
echo ${myarray[0]} ${myarray[4]}

We run the script again and we get:

$ ./arrays.sh
Hello Friday

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Categories: Système, Tutoriel Tags: , , ,

Linux Users and Sudo

11/03/2019 Comments off

Introduction

users sudoBefore we proceed, it would be best to cover some basic user administration topics that will be very useful in later chapters. Adding Users

One of the most important activities in administering a Linux box is the addition of users. Here you’ll find some simple examples to provide a foundation for future chapters. It is not intended to be comprehensive, but is a good memory refresher. You can use the command man useradd to get the help pages on adding users with the useradd command or the man usermod to become more familiar with modifying users with the usermod command.

Who Is the Super User?

The super user with unrestricted access to all system resources and files in Linux is the user named root. This user has a user ID, of 0 which is universally identified by Linux applications as belonging to a user with supreme privileges. You will need to log in as user root to add new users to your Linux server.

Debian Note: When installing Ubuntu Linux systems, you are prompted to create a primary user that is not root. A root user is created but no password is set, so you initially cannot log in as this user. The primary user can become the root user using the sudo su - command that will be discussed later.

How To Add Users

Adding users takes some planning; read through these steps below before starting:

1) Arrange your list of users into groups by function. In this example there are three groups « parents« , « children » and « soho« .

Parents    Children     Soho
Paul       Alice        Accounts
Jane       Derek        Sales

2) Add the Linux groups to your server:

[root@bigboy tmp]# groupadd parents
[root@bigboy tmp]# groupadd children
[root@bigboy tmp]# groupadd soho

3) Add the Linux users and assign them to their respective groups

[root@bigboy tmp]# useradd -g parents paul
[root@bigboy tmp]# useradd -g parents jane
[root@bigboy tmp]# useradd -g children derek
[root@bigboy tmp]# useradd -g children alice
[root@bigboy tmp]# useradd -g soho accounts
[root@bigboy tmp]# useradd -g soho sales

If you don’t specify the group with the -g, RedHat/Fedora Linux creates a group with the same name as the user you just created; this is also known as the User Private Group Scheme. When each new user first logs in, they are prompted for their new permanent password.

4) Each user’s personal directory is placed in the /home directory. The directory name will be the same as their user name.

[root@bigboy tmp]# ll /home
drwxr-xr-x 2 root root 12288 Jul 24 20:04 lost found
drwx------ 2 accounts soho 1024 Jul 24 20:33 accounts
drwx------ 2 alice children 1024 Jul 24 20:33 alice
drwx------ 2 derek children 1024 Jul 24 20:33 derek
drwx------ 2 jane parents 1024 Jul 24 20:33 jane
drwx------ 2 paul parents 1024 Jul 24 20:33 paul
drwx------ 2 sales soho 1024 Jul 24 20:33 sales
[root@bigboy tmp]#

Lire la suite…

tmux & screen cheat-sheet

08/03/2019 Comments off

screen and tmux

A comparison of the features (or more-so just a table of notes for accessing some of those features) for GNU screen and BSD-licensed tmux.

The formatting here is simple enough to understand (I would hope). ^ means ctrl+, so ^x is ctrl+x. M- means meta (generally left-alt or escape)+, so M-x is left-alt+x

It should be noted that this is no where near a full feature-set of either group. This – being a cheat-sheet – is just to point out the most very basic features to get you on the road.

Trust the developers and manpage writers more than me. This document is originally from 2009 when tmux was still new – since then both of these programs have had many updates and features added (not all of which have been dutifully noted here).

Action tmux screen
start a new session tmux OR
tmux new OR
tmux new-session
screen
re-attach a detached session tmux attach OR
tmux attach-session
screen -r
re-attach an attached session (detaching it from elsewhere) tmux attach -d OR
tmux attach-session -d
screen -dr
re-attach an attached session (keeping it attached elsewhere) tmux attach OR
tmux attach-session
screen -x
detach from currently attached session ^b d OR
^b :detach
^a ^d OR
^a :detach
rename-window to newname ^b , <newname> OR
^b :rename-window <newn>
^a A <newname>
list windows ^b w ^a w
list windows in chooseable menu   ^a « 
go to window # ^b # ^a #
go to last-active window ^b l ^a ^a
go to next window ^b n ^a n
go to previous window ^b p ^a p
see keybindings ^b ? ^a ?
list sessions ^b s OR
tmux ls OR
tmux list-sessions
screen -ls
toggle visual bell   ^a ^g
create another window ^b c ^a c
exit current shell/window ^d ^d
split window/pane horizontally ^b «  ^a S
split window/pane vertically ^b % ^a |
switch to other pane ^b o ^a <tab>
kill the current pane ^b x OR (logout/^D)  
collapse the current pane/split (but leave processes running)   ^a X
close other panes except the current one ^b !  
cycle location of panes ^b ^o  
swap current pane with previous ^b {  
swap current pane with next ^b }  
show time ^b t  
show numeric values of panes ^b q  
toggle zoom-state of current pane (maximize/return current pane ^b z  
break the current pane out of its window (to form new window) ^b !  

Source: dayid.org