Jawaban:
Jika Anda kesulitan membaca manual daripada membuat teka-teki:
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.
...
Pathname Expansion
After word splitting, unless the -f option has been set, bash scans
each word for the characters *, ?, and [. If one of these characters
appears, then the word is regarded as a pattern, and replaced with an
alphabetically sorted list of filenames matching the pattern (see
Pattern Matching below). If no matching filenames are found, and the
shell option nullglob is not enabled, the word is left unchanged.
...
Pattern Matching
Any character that appears in a pattern, other than the special pattern
characters described below, matches itself. ...
The special pattern characters have the following meanings:
...
[...] Matches any one of the enclosed characters. A pair of
characters separated by a hyphen denotes a range
expression; any character that falls between those two
characters, inclusive, using the current locale's
collating sequence and character set, is matched.
file[1-3]
mengembang ke file bernama file1
, file2
, file3
. Ekspansi nama file hanya terjadi jika ada file yang cocok. Jika tidak, polanya dibiarkan apa adanya. Oleh karena itu, dengan file bernama file1
, file2
, file3
, file[1-3]
memperluas ke file1 file2 file3
. Tanpa file-file ini, itu tidak berkembang, dan tetap seperti file[1-3]
. Dengan {...}
, nama file tidak harus ada, jadi file{1..3}
perluas file1 file2 file3
terlepas dari file yang ada atau tidak ada.
shopt -s nullglob
sebelum - Anda akan memahaminya. Lihat mywiki.wooledge.org/glob