Bash brace expansion

1. How do you use the brace expansion in bash?
2. What is the brace expansion?
3. What does mean in bash?
4. What does the $$ variable expand to in bash?
5. What is one difference between brace expansion and globs?
6. What do parentheses do in bash?
7. What is filename expansion?
8. What do curly brackets mean in bash?
9. What do curly brackets mean in Linux?

How do you use the brace expansion in bash?

Brace expansion is enabled via the "set -B" command and the "-B" command line option to the shell and disabled via "set +B" and "+B" on the command line.

What is the brace expansion?

Brace expansion is a mechanism by which arbitrary strings may be generated. ... Patterns to be brace expanded take the form of an optional preamble , followed by either a series of comma-separated strings or a sequence expression between a pair of braces, followed by an optional postscript .

What does mean in bash?

has absolutely no meaning to bash , so is passed unmodified as an argument to the command executed, here find . On the other hand, ; has a specific meaning to bash . It is normally used to separate sequential commands when they are on the same command line.

What does the $$ variable expand to in bash?

The ' $ ' character introduces parameter expansion, command substitution, or arithmetic expansion. ... Bash uses the value formed by expanding the rest of parameter as the new parameter ; this is then expanded and that value is used in the rest of the expansion, rather than the expansion of the original parameter .

What is one difference between brace expansion and globs?

What is one major difference between brace expansion and globs? Globs create a list; brace expansion matches pattern. Brace expansion requires files to exist; globs do not. Brace expansion creates a list; globs match the list of pathnames.

What do parentheses do in bash?

Parentheses denote a subshell in bash. To quote the man bash page: (list) list is executed in a subshell environment (see COMMAND EXECUTION ENVIRONMENT below). Variable assignments and builtin commands that affect the shell's environment do not remain in effect after the command completes.

What is filename expansion?

Another way to save time in your commands is to use special characters to abbreviate filenames. You can specify many files at once by using these characters. This feature of the shell is sometimes called "globbing."

What do curly brackets mean in bash?

3.2. 5.3 Grouping Commands

Bash provides two ways to group a list of commands to be executed as a unit. ... Placing a list of commands between curly braces causes the list to be executed in the current shell context. No subshell is created. The semicolon (or newline) following list is required.

What do curly brackets mean in Linux?

The end of the variable name is usually signified by a space or newline. ... The curly braces tell the shell interpreter where the end of the variable name is.