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Unix
Unix is a family of operating systems primarily designed for servers, mainframes, and high-end workstations. First created in 1969, Unix systems are renowned for their security and stability.
1,127 Questions
What is a file command used to create or start a new file?
The 'touch' command creates a new empty file in Unix.
What is meaning of open source operating sysytem?
Recursive program/function/... is something that executes/invokes itself.
For example rm -rf will delete everything in a directory, also invoking "rm -rf" on every folder in this directory.
Isochoric process is a process in which change in pressure and temperature takes place in such a way that the volume of the system remains constant.
In computing, an inode (index node) is a data structure found in many Unix file systems. Each inode stores all the information about a file system object (file, directory, device node, socket, pipe, etc.), except data content and file name.
The reason for designating these as "i" nodes is unknown. When asked, Unix pioneer Dennis Ritchie replied:
In truth, I don't know either. It was just a term that we started to use. "Index" is my best guess, because of the slightly unusual file system structure that stored the access information of files as a flat array on the disk, with all the hierarchical directory information living aside from this. Thus the i-number is an index in this array, the i-node is the selected element of the array. (The "i-" notation was used in the 1st edition manual; its hyphen was gradually dropped.)
What is the difference between the ls and ls -al commands?
ls --> will list the files and directories
but
ls -a --> will list the hidden files too,
by
Dhanush M
The mesg command displays the current state of messaging (write, talk, etc.) for a user. You can also use it to turn on and off messaging (mesg y, mesg n).
What are the programs 'gdm' and 'kdm' used for?
The GNOME Display Manager (GDM) and KDE Display Manager (KDM) are X display managers that allows a user to start an X session on an X server.
In other words, the display manager shows the login screen when nobody is logged in. After it checks your username and password, it hands off the work to the actual display manager (e,g, GNOME, KDE, Xfce, LXDE).
GDM uses the GTK windowing toolkit, while KDM uses the KDE counterpart, Qt.
What is the running process of vi editor?
Your question is uncleear; every time you start the 'vi' editor you get another process.
What is the procedure of execute a script in shell in ubantu?
For any Unix or Linux based operating system, make the text file readable and executable and then invoke (call) it by the file name, which will execute the script.
How Auto mains Failure panel works?
First of all let us understand what is AMF?
Generally all the major industries/companies/institution have the DG for power back up , but when main power is cut off , someone has to go to start the DG and this takes time and also a man has to be kept for this purpose. So to eliminate this process PLC panel is installed to Auto start the DG when main power fails.
Working is as follows:-
when main power goes , a signal is received to PLC and after a delay DG starts . When the Main supply fail signal is received by PLC then after a delay time, output for ACB/Contactor of DG is ON and DG starts automatically. Also the ACB/Contractor of main transformer if sent OFF Command. When main power comes then the signal is again sent to PLC and PLC off the ACB/Contactor of DG and after 2 seconds it on the ACB/Contactor of main transformer and after 30 seconds it off the DG. DG is sent OFF command a little late so that the load beard by DG for a long time can be compensated by running at no load for some time.
If for example we wanted to make i subdirictory called foo
in Linux or UNIX it you use
mkdir foo
to change into it you would use
CD foo
to remove the directory
rmdir foo
but this will only work if the directory is empty
to remove the directory called foo when it is not empty use
rm -rf foo
but please be sure this is what you really want to do.
What are examples of command line of wildcard characters?
You need to supply the possible answers you are looking for. In general, * ? + . etc are wildcard characters, along with [] for set inclusions, etc.
Are system calls part of kernel?
Yes, they are the interface to kernel functionality. To quote wikipedia: a system call is how a program requests a service from an operating system's kernel that it does not normally have permission to run
Where can you find questions and answers on the topic of Unix?
Here is the link to the subcategory of Unix:
What file extensions are used to identify command shell scripts?
For windows, you might use .cmd, .bat as common file extensions.
Unix doesn't use file extensions as associations, so no file extension needs to be used in the Unix environment. A shell script in Unix is simply a text file with any name that is readable and executable.
However, file extensions are typically used in Unix as a documentation aid that states that the file is a shell script. Common extensions are .sh, .csh, .ksh, .tcsh, .zsh, etc.
What is the difference between absolute path name and relative path name in Unix?
Absolute path: Path from root directory (it is the same place, wherever the current path is)
Relative path: Relative to the current path.
What is the command for listing all files ending in small letters in unix?
Try the following:
ls *[a-z]
What Refers to directing the output of one command to the input of a second command?
The 'pipe' symbol connects the output of one command to the input of another (|)
What is the special editing command to edit the user account information file?
This command should be used very carefully, and may only be used by the administrative/root account:
vipw
