freeCodeCamp/guide/spanish/linux/some-usages-for-linux/automating-tasks/index.md

title	localeTitle
Automating Tasks	Tareas de automatización

Tareas de automatización o programación de tareas

Hay una característica de Linux que se aprovecha exclusivamente en un servidor web, conocido como CRON Como sabemos, una de las características más convincentes de cualquier servidor web es que siempre es Encendido y siempre conectado a internet. Esto significa que podemos instruir nuestro servidor para realizar tareas automáticamente, sin que tengamos que ingresar un comando en una concha. Uno de los programas más utilizados para ejecutar otros programas. Con una frecuencia regular se llama cron . Echemos un vistazo a cómo usar cron para programar un programa para ser ejecutado.

El programa cron es parte de una familia de programas llamados daemons . Un demonio es un programa que siempre se está ejecutando en el fondo de nuestra computadora. Primero, vamos a ver si cron está ejecutando. Podemos obtener una lista de todos los programas en ejecución. con el comando ps mientras se usa el indicador -A :

`` `{r, engine = 'bash', eval = FALSE} ps -A

PID TTY TIEMPO CMD

1? 00:00:13 systemd

2? 00:00:00 Kreadd

3? 00:00:03 ksoftirqd / 0

5? 00:00:00 kworker / 0: 0H

7? 00:00:11 rcu_sched

8? 00:00:00 rcu_bh

9? 00:00:00 migración / 0

...

You probably have a huge list of programs in your terminal now! Instead of 
 shifting through this listing line-by-line, let's pipe the output of this command 
 to `grep` and we'll look for `cron`: 

{r, engine = 'bash', eval = FALSE} ps -A | grep "cron"

1273? 00:00:01 cron

# You might or might not get a `cron` running . 
 
 Looks like the `cron` daemon is running! In order to assign programs to be 
 executed with `cron` we need to edit a special text file called the `cron` 
 table. Before we edit the `cron` table we need to select the default text 
 editor. If you like using `nano` (the text editor we've been using throughout 
 this book) then enter `select-editor` into the console, type in the number 
 that corresponds to `nano` (usually `2`) and then press enter: 

{r, engine = 'bash', eval = FALSE} editor seleccionado

Seleccione un editor. Para cambiar más tarde, ejecute 'seleccionar-editor'.

1. / bin / ed

2. / bin / nano <---- más fácil

3. /usr/bin/vim.basic

4. /usr/bin/vim.tiny

Elija 1-4 [2]:

Now that we've chosen a text editor we can edit the `cron` table using the 
 command `crontab -e` (**`cron`** **tab**le **e**dit) which will automatically 
 open `nano` with the appropriate file. 

{r, engine = 'bash', eval = FALSE} crontab -e

Edite este archivo para introducir tareas para ser ejecutadas por cron.

m h dom dom dow comando

Let's go over the layout of the `cron` table. First you should notice that any 
 text after a pound sign (`#`) is a comment, so it's not seen by `cron` (just 
 like bash comments). The `cron` table has six columns: 
 
 1. Minute (`m`) 
 2. Hour (`h`) 
 3. Day of Month (`dom`) 
 4. Month (`mon`) 
 5. Day of Week (`dow`) 
 6. Command to be run (`command`) 
 
 Each column is separated by a single space in the table. The first five columns 
 allow you to specify when you want a particular command to be run. Only certain 
 values are valid in each column: 
 
 1. Minute: `00 - 59` (A particular minute in an hour) 
 2. Hour: `00 - 23` (0 is the midnight hour) 
 3. Day of Month: `01 - 31` (1 is the first day of the month) 
 4. Month: `01 - 12` (1 is January) 
 5. Day of Week `0 - 6` (0 is Sunday) 
 
 There are also a few other characters that are valid in the `cron` table. The 
 most commonly used character is a star (`*`) which represents *all* of the 
 possible values in a column. So a star in the Minute column means "run every 
 minute," and a star in the Hour column means "run during every hour." 
 Knowing this let's make our first entry in the `cron` table. If we want a 
 command to be executed every minute, during every hour, on every day of the 
 month, during every month, on every day of the week, then we can put stars in 
 all of the first five 
 columns, followed by the command that we want to run. In this case the command 
 that `cron` will run every minute will be `date >> ~/date-file.txt`, which will 
 append the date and time when the command is executed to a file in our home 
 directory called `date-file.txt`. This is what your `cron` table should look 
 like before you save and exit from `nano`: 

Edite este archivo para introducir tareas para ser ejecutadas por cron.

m h dom dom dow comando

• * * * * fecha >> ~ / fecha-archivo.txt

Save and exit `nano` just like you would for a regular text file and then wait 
 a little bit! After a minute has gone by use `cat` to look at `~/date-file.txt`: 

{r, engine = 'bash', eval = FALSE} discos compactos cat fecha-archivo.txt

Jue 8 jun 18:50:01 UTC 2017

Look like our entry in the `cron` table is working! Wait another minute and then 
 look at the file again: 

{r, engine = 'bash', eval = FALSE} cat fecha-archivo.txt

Jue 8 jun 18:50:01 UTC 2017

Jue 8 jun 18:51:01 UTC 2017

Unless we delete the line that we entered in the `cron` table, the output from 
 `date` will be appended to `date-file.txt` every minute. 
 
 The single line of bash `date >> ~/date-file.txt` is a much simpler program than 
 we would probably use in a `cron` table, though it's good for illustrating how 
 a `cron` table works. If you want to do more complex tasks with `cron` it's 
 better for `cron` to execute a bash script that you've written in advance. That 
 way you can just specify `bash /path/to/script.sh` in the last column of the 
 table. 
 
 Using stars in all columns is the simplest line of a `cron` table, so let's 
 look at some examples of more complex table entries: 

m h dom dom dow comando

00 * * * * bash /path/to/script.sh # Se ejecuta cada hora al comienzo de la hora 00 12 * * * bash /path/to/script.sh # Se ejecuta todos los días al mediodía

• 12 * * * bash /path/to/script.sh # Se ejecuta cada minuto entre las 12 pm y las 12:59 pm 00 00 05 * * bash /path/to/script.sh # Se ejecuta el quinto día de cada mes a la medianoche 00 00 * 07 * bash /path/to/script.sh # Se ejecuta todos los días en el mes de julio a la medianoche 00 00 * * 2 bash /path/to/script.sh # Se ejecuta todos los martes a la medianoche

Besides numbers and the star there are a few other characters that you can use 
 in `cron` table columns including a hyphen (`-`) for specifying ranges and a 
 comma (`,`) for specifying lists of items. For example `00-29` in the Minutes 
 column would specify the first thirty minutes of an hour, while `1,5` in the 
 Day of Week column would specify Monday and Friday. 
 
 Let's take a look at another example of a `cron` table that uses hyphens and 
 ranges so you can get a sense of how each character works. 

m h dom dom dow comando

00-04 * * * * bash /path/to/script.sh # Se ejecuta cada minuto durante los primeros cinco minutos de cada hora 00 00 * * 0,6 bash /path/to/script.sh # Se ejecuta a la medianoche todos los sábados y domingos 00 03 01-15 * * bash /path/to/script.sh # Se ejecuta a las 3am durante los primeros quince días de cada mes 00,30 * * * * bash /path/to/script.sh # Se ejecuta al inicio y en la mitad de cada hora 00 00,12 * * * bash /path/to/script.sh # Se ejecuta todos los días a la medianoche y al mediodía 00 * 01-07 01,06 * bash /path/to/script.sh # Se ejecuta al comienzo de cada hora durante los primeros siete días de los meses de enero y junio `` `

Un programa que está siendo ejecutado por cron es tan poderoso como su imaginación. puede estirar Si estás familiarizado con la red social. Twitter entonces puede que hayas encontrado algo de Twitter Cuentas que crean publicaciones automáticamente como Acuario Emoji , Fotos de frutas viejas , o Gritos sin fin Muchos de estos "bot" las cuentas están activadas por cron , que utiliza la API HTTP de Twitter para publicar tweets regularmente.