Bash Select Command

1. How do I select text in bash?
2. What is Linux select command?
3. How can I create a select menu in shell script?
4. What is $? In Bash?
5. How do I select in terminal?
6. How do I select everything in terminal?
7. Is Select blocking call?
8. Is Select thread safe?
9. What does select () do in C?
10. What is if in shell script?
11. What is if Z in shell script?
12. What is option in shell script?

How do I select text in bash?

You can highlight text in gedit and hit Ctrl+C , and then paste it into a terminal window using Ctrl+Shift+V . The key combination Ctrl+Insert is the same as Ctrl+Shift+C , and the combination Shift+Insert is the same as Ctrl+Shift+V .

What is Linux select command?

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 can I create a select menu in shell script?

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 $? In Bash?

$? is a special variable in bash that always holds the return/exit code of the last executed command. You can view it in a terminal by running echo $? . Return codes are in the range [0; 255]. A return code of 0 usually means everything is ok.

How do I select in terminal?

Pressing Ctrl + Shift + Space will activate it. It's got vim-like key bindings. v or V will select à la vim 's visual mode, y will yank, Esc will exit selection mode. Screen and Emacs M-x shell , for example, allow for keyboard access to the scrollback buffer.

How do I select everything in terminal?

Like in other editors ctrl+A does the job for select all.

Is Select blocking call?

By using the select() call, you do not issue a blocking call until you know that the call cannot block. The select() call can itself be blocking, nonblocking, or, for the macro API, asynchronous.

Is Select thread safe?

According to the Linux manual page, select is a thread safe function and a cancellation point. On Linux some operating systems, one thread will successfully enter select , while the other threads would be blocked (the body of select is a critical section).

What does select () do in C?

The select() function tests file descriptors in the range of 0 to nfds-1. If the readfds argument is not a null pointer, it points to an object of type fd_set that on input specifies the file descriptors to be checked for being ready to read, and on output indicates which file descriptors are ready to read.

What is if in shell script?

Conditions in Shell Scripts

An if-else statement allows you to execute iterative conditional statements in your code. We use if-else in shell scripts when we wish to evaluate a condition, then decide to execute one set between two or more sets of statements using the result.

What is if Z in shell script?

The -z flag causes test to check whether a string is empty. Returns true if the string is empty, false if it contains something. NOTE: The -z flag doesn't directly have anything to do with the "if" statement. The if statement is used to check the value returned by test.

What is option in shell script?

The getopts options are used in shell scripts to parse arguments passed to them. When arguments are passed on the command line, getopts parse those arguments instead of command lines. Options are written starting with a hyphen (-), followed by the letter. For example, -a, -b, -c, -d, etc.