I've been finding more and more uses for the
{}
pattern-expansion characters in
csh
,
tcsh
, and
bash
. (Other shells can use
{}
, too; see article
15.3
.) They're similar to
*
,
?
, and
[]
(
15.2
)
, but they don't match filenames the way that
*
,
?
, and
[]
do. You can give them arbitrary text (not just filenames) to expand - that "expand-anything" ability is what makes them so useful.
Here are some examples to get you thinking:
To fix a typo in a filename (change fixbold5.c to fixbold6.c ):
%mv fixbold{5,6}.c
An easy way to see what the shell does with
{}
is by adding
echo
(
8.6
)
before the
mv
:
%echo mv fixbold{5,6}.c
mv fixbold5.c fixbold6.c
To copy filename to filename.bak in one easy step:
%cp filename{,.bak}
To print files from other directory(s) without retyping the whole pathname:
%lpr /usr3/hannah/training/{ed,vi,mail}/lab.{ms,out}
That would give lpr ( 43.2 ) all of these files:
/usr3/hannah/training/ed/lab.ms /usr3/hannah/training/ed/lab.out /usr3/hannah/training/vi/lab.ms /usr3/hannah/training/vi/lab.out /usr3/hannah/training/mail/lab.ms /usr3/hannah/training/mail/lab.out
...in one fell swoop!
To edit ten new files that don't exist yet:
%vi /usr/foo/file{a,b,c,d,e,f,g,h,i,j}
That would make
/usr/foo/filea
,
/usr/foo/fileb
, ...
/usr/foo/filej
. Because the files don't exist before the command starts, the wildcard
vi
/usr/foo/file[a-j]
would
not
work (
9.4
)
.
An easy way to step through three-digit numbers 000, 001, ..., 009, 010, 011, ..., 099, 100, 101, ... 299 is:
foreach |
foreach n ({0,1,2}{0,1,2,3,4,5,6,7,8,9}{0,1,2,3,4,5,6,7,8,9}) ... Do whatever with the number $n ... end |
---|
Yes,
csh
also has built-in arithmetic, but its
@
operator (
47.4
)
can't make numbers with leading zeros. This nice trick shows that the
{}
operators are good for more than just filenames.
To create sets of subdirectories:
%mkdir man
%mkdir man/{man,cat}{1,2,3,4,5,6,7,8}
%ls -F man
cat1/ cat3/ cat5/ cat7/ man1/ man3/ man5/ man7/ cat2/ cat4/ cat6/ cat8/ man2/ man4/ man6/ man8/
To print ten copies of the file project_report (if your lpr ( 43.2 ) command doesn't have a -#10 option):
%lpr project_repor{t,t,t,t,t,t,t,t,t,t}
-