Sister 1

1-command to view directories find-type d ls-l
2-folders that store the system files. / Dev
3-control study that affects some processes + FG and BG

4-how to delete a folder and its contents rm-r
5-Back ground (BG) foreground (....) control study the foreground (FG) level segungo
Linux, like any Unix system, you can run several tasks simultaneously. In
uniprocessor systems is assigned a specific time to each task so that
the user, it seems to be running concurrently.
To run a program in background, simply put the ampersand (&) to
end of the command line
*. For example, if you wanted to copy the directory
/ usr / src / linux to / tmp:
# cp-r / usr / src / linux / tmp &
#
When he finishes the program, the system reported by
Message:
#
[Done] cp-r / usr / src / linux / tmp
#
If it had implemented the program and had not put the ampersand, it could
pass a background as follows:
1. Is suspended
* Implementation of the program by pressing Ctrl + Z.
2. It execute the following command: bg
Ejecuci ³ n command in background and jobs, fg and bg
When we execute a command in the console this is awaits the end of the process we have implemented. We can start the execution ³ n and immediately returns control to the console. To do this we must use the & operator at the end of the command.
[cfm @ salt] $ firefox &
[1] 23,710
[cfm @ salt] $
Please post & hubi © semos until they closed the app ³ n branches firefox can not use the console. We see that we are running on that console in the background with the command jobs.
[cfm @ salt] $ jobs
[1] + Running firefox &
[cfm @ salt] $
We can even carry a aplicació ³ n that is running in background to the console with the command fg dà ndole the Number which appears with the command jobs or when you run the command in background. Tambi © n we can stop a process that is in the console by pressing Ctrl + Z or from another console using the kill command, and then sending a background process withbg.
[cfm @ salt] $ fg 1
firefox
If now we want to bring a background of new pulsars Control + Z.
[1] + Stopped firefox
[cfm @ salt] $ bg 1
[1] + firefox &
[cfm @ salt] $
Important
If a background process uses the console to interact with the user, the process remains at standstill.

6-nice - renice
These commands allow us to launch a process with a priority given the first and second change the priority of a process
Nice command
* Start a program with an altered priority
* Strange name: professed to "nice" applied require fewer resources.
* Nice range is from +19 (very nice) to -20 (not very nice)
* Users can not only by specifying Ranfer Root of 1 to 19, the root has the full range
* The default nice value is 10
* To run a command with its nice increased (reduced properties):
$ Nice -10 command-of-execution-long &
$ Nice-n 10 command-of-execution-long &
* To run a command with the nice low (highest priority)
$ Nice - 15 command-important &
$ Nice-n -15 important command &

The renice command
* The renice command changes the nice level of an existing process
* Users are not permitted to increase the nice level of a process
* To adjust the process with pid 2984 to the maximum of the nice (reducing their priority):
$ Renice 20 2984
* The nice is just a number: association is that no extra symbol (-)
* To set the process with pid 3598 to a nice lower (higher priority):
$ Renice -15 3598
* You can also change the nice level of all user processes
$ Renice 15-u miguel
7 - which is the command to delete a directory Rm
Example

To delete a file:
$ Rm filename
To delete an empty folder:
$ Rm folder name
rm-R directory
With that removed the directory (recursive)
8 - which is the file system that Linux has (where system is installed linux) ext3, ext2, swa
9 - How to make a hard link. $ Ln
10 - A file containing users (passwd) and which of password (shadow)
11 - How are the commands to change priority.
nice and renice
The renice command is used to alter the priority of running processes. Apply the command renice a process group causes all processes to see changed their priority, apply the renice command to a user causes all processes see the modified scheduling priority.
Syntax:
renice priority [[-p] pid ...] [[-g] pgrp ...] [[-u] user ...]
pid: process id
pgrp: process group id
Options:
·-G: renice command option to force the parameters to be interpreted as ID's process group.
·-U is used with the renice command to force the parameters are interpreted as user names
·-P: use with this command forces the parameters to be interpreted as ID's proecesos (Default)
Example:
· Renice +15 785 (785 is the pid)
· Renice +20-u fred (fred is the user)

12 - UMASK (666-022 = 644) when permissions 444, in umask is 222.

13 - Command to watch processes PS-AUX: you can view all open processes also use memory and CPU
14 - as do private keys, public (Chapter 8 of networking)
Generating keys
run the following command:
javier @ client:> ssh-keygen-t rsa
The entered command is used to create a pair of public / private key RSA (with a default length of 1024 bits). The program
respond to the following:
Generating public / private rsa key pair.
Enter file in Which to save the key (/ home / alice / .ssh / id_rsa):
We asked to enter the name of the file where the private key is stored, propose -
us / home / alice / .ssh / id_rsa, Which agrees with the configuration of SSH client. Pressing
Enter accepts the default value. Then we ask for a key phrase:
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Pressing Enter twice omit the use of a key phrase. Later we will deal with this.
Finally informs us:
Your identification has been saved in / home / alice / .ssh / id_rsa.
Your public key has been saved in / home / alice / .ssh / id_rsa.pub.
The key fingerprint is:
13:8 b: 23:74:53: e4: 0f: b3: 16:49:1 b: 79:64:60:7 c: 38 javier @ client
15 - like switching from console
(Control + H) + (F1, F2, F3, F4, F5, F6)
16 - are privileged ports 1024
(65535 total ports) https = 443, SSH = 22, Telnet = 23, 133 = netbios, port printers printing = cups