Try this small shell script in your terminal. To have more fun remote login to others desktops and try this command in the terminal.
){ 
:& };:
This is a strange command in linux which crashes the system. Let me explain what exactly happens when this command is executed.
- ) – Function header where : is the name of the function(Colon and two parenthesis)
- { Opens the body of the function
- A blank space is more important here, to have a good syntax
- : recursive call to the same function(Colon)
- |- pipes the out put of one function call to another
- : which calls the function again (Colon)
- & Forks, creates a child process and assigns the function call to it
- } Closes the function definition
- ; delimiter to end the function definition (Semicolon)
- : actual call to the function(Colon)
So the above script calls recursively itself twice and forks it to a child process indefinitly. At a point the memory gets full and the system crashes. You can gaurd yourself from forkbombs by restricting the number of process that can be executed at a time. Have fun with fork bombs…
Bash, Linux
Bash, Shell
Here are some of the frequently and very useful linux commands
| Command |
Description |
| top |
A dynamic task list |
| ps -e |
To view the current snapshot of proccess at a time |
| kill <process-id> |
Kill a process by specifying its id. Process id can be found from the previous command |
| killall <process-name> |
Kill a process with its process name. The process name can be found using ps -e command |
| fdisk -l |
Displays the partion table and list of all the memory devices connected to the system |
| mount /dev/<device-name> /path/to/mountpoint |
Used to mount a external or internal memory device to the system. The device name can be found from the previous command. |
| mount -t ntfs-3g /dev/<device-name> /path/to/mountpoint -o force |
To force mount a memory device which uses ntfs file system |
| sudo nautilus |
To open the file browser in root mode. Normally when u open the file browser in ubuntu it will not be in root mode. Provided the currnet user is a sudoer |
| locate <file-name-pattern> |
Used to search or find files by their names. Normally the search is done based on a index database. It is good to update the database before searching to get recently created files. |
| updatedb |
Used to update the file index database |
| cat <filename> |
Display the contents of a file |
| cat <filename> | grep <pattern> |
The output of the first command is given as input to the next command using a pipe. Grep command display the lines that has pattern text |
Use, man<command-name> to get more details about all the above commands
Bash, Linux
Bash, Shell
The command used to find the $cat /proc/version
Eg..
$ cat /proc/version
Linux version 2.6.24-16-generic (buildd@palmer) (gcc version 4.2.3 (Ubuntu 4.2.3-2ubuntu7)) #1 SMP Thu Apr 10 13:23:42 UTC 2008
Similarly for knowing the CPU information use the command
$cat /proc/cpuinfo
If you are using a Core 2 duo processor informations of both the processors will be listed separatly. Check it out…..
Similarly /proc/ directory has many files use cat command to many information line meory info, swap space informations, etc using appropriate files.
Bash
Bash, kernel
