UNIX for Beginners Questions & Answers

Brace Expansion
Brace expansion is a mechanism by which arbitrary strings may be generated. This mechanism is similar to pathname expansion, but the filenames generated need not exist. 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.
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A sequence expression takes the form {x..y[..incr]}, where x and y are either integers or single characters, and incr, an optional increment, is an integer.

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Brace expansion is performed before any other expansions, and any characters special to other expansions are preserved in the result. It is
strictly textual. Bash does not apply any syntactic interpretation to the context of the expansion or the text between the braces.