select command in Linux is used to create a numbered menu from which a user can select an option. If the user enters a valid option then it executes the set of command written in select block and then ask again to enter a number, if a wrong option is entered it does nothing.
How do you select all data in Unix?
How To “Select All” In Vim/Vi?
- Use ggVG To Select All. All content of a file can be selected by using the Visual Mode of Vim or Vi. …
- Use 99999yy To Select and Copy All. There is an alternative way that can be used to select and copy all content. …
- Use $yy To Select and Copy All.
How do I select in bash?
Bash select Construct
If the user enters a number that corresponds to the number of one of the displayed items, then the value of [ITEM] is set to that item. The value of the selected item is stored in the variable REPLY . Otherwise, if the user input is empty, the prompt and the menu list are displayed again.
What is select in sockets?
The select function is used to determine the status of one or more sockets. For each socket, the caller can request information on read, write, or error status. The set of sockets for which a given status is requested is indicated by an fd_set structure.
What is select loop?
The select loop provides an easy way to create a numbered menu from which users can select options. It is useful when you need to ask the user to choose one or more items from a list of choices.
How do you select multiple lines in vi?
Place your cursor anywhere on the first or last line of the text you want to manipulate. Press Shift+V to enter line mode. The words VISUAL LINE will appear at the bottom of the screen. Use navigation commands, such as the Arrow keys, to highlight multiple lines of text.
How do I copy and paste in vi?
Press d to cut or y to copy. Move the cursor to the place where you want to paste. Press p to paste contents after the cursor or P to paste before the cursor.
How do you select in Linux?
- Click at the start of the text you want to select.
- Scroll the window to the end of the text you want select.
- Shift + click the end of your selection.
- All text between your first click and your last Shift + click is now selected.
- Then you can Ctrl + Shift + C your selection out of there.
How do I select a shell in Linux?
To change your shell with chsh:
- cat /etc/shells. At the shell prompt, list the available shells on your system with cat /etc/shells.
- chsh. Enter chsh (for “change shell”). …
- /bin/zsh. Type in the path and name of your new shell.
- su – yourid. Type in su – and your userid to relog in to verify that everything works correctly.
How does select () work?
select() works by blocking until something happens on a file descriptor (aka a socket). What’s ‘something’? Data coming in or being able to write to a file descriptor — you tell select() what you want to be woken up by. … You fill up a fd_set structure with some macros.
Are sockets TCP or UDP?
Because web servers operate on TCP port 80, both of these sockets are TCP sockets, whereas if you were connecting to a server operating on a UDP port, both the server and client sockets would be UDP sockets.
What does select () do in C?
A better solution is to use the select function. This blocks the program until input or output is ready on a specified set of file descriptors, or until a timer expires, whichever comes first. This facility is declared in the header file sys/types.