Re: shell commands - exclusion
On Friday 06 February 2009 02:55, Chris Whitehouse wrote:
I think you should be able to do it with a combination of -prune and
-delete (or -exec rm -rf {} \; ) on a find command. Substitute your
other commands for rm -rf in the -exec above.
I would give you a working example except I can't figure out the syntax
for -prune. Examples from google don't seem to work in (my) FreeBSD.
[skip to the end for a simple answer without the lengthy exposition]
find(1) can be confusing, especially if you think of the ``actions''
( -print, -exec and -delete plus their variants like -ls and -ok ) as
something different from the ``tests'' ( -name and so on), or if you don't
take account of the evaluation order.
A find expression comprises a number of what the manpage calls primaries, each
of which evaluates as true or false. (It may also have a side-effect,
like -print whose side-effect is to print the name). Primaries can be
combined with -and (which is usually implied) or -or. Where -and and -or both
occur, find will group the -anded primaries together before evaluation.
Taking one of your examples below,
find . -print -or -prune -name dir1
this is grouped as
find . -print -or \( -prune -and -name dir1 \)
find will then evaluate the whole expression from left to right for each
pathname in the tree it's looking at, stopping within each set of (implied)
parentheses and within the overall expression as soon as it can determine
truth or falsehood. (This is what's referred to in programming as
short-circuiting in boolean expressions).
If primaries are linked by -and, find can stop at the first one that's false,
knowing the expression is false; if they're linked by -or it can stop at the
first one that's true, knowing the expression is true. Otherwise it has to
evaluate the whole expression.
Before it does this, though, find checks for side-effects. If there isn't a
side-effect anywhere in your expression, find will put brackets round the
whole expression and a -print after it.
Looking at your examples:
chr...@pcbsd% find .
(No expression). Find adds a -print, so this is the same as the next one:
chr...@pcbsd% find . -print
.
./test.mov
./test.mpg
./dir1
./dir1/file1
./dir1/file2
./file3
-print is always true so the expression is true for each name - they get
printed as a side-effect.
chr...@pcbsd% find . -print -o -prune dir1
find: dir1: unknown option
-prune doesn't take an argument, so dir1 is a syntax error.
chr...@pcbsd% find . -print -o -prune -name dir1
find evaluates the print, which prints each name as its side-effect. -print
evaluates as true. Since it's in an -or, find can stop there, so it never
sees the second expression ( -prune -and -name dir1: the -and is implicit).
.
./test.mov
./test.mpg
./dir1
./dir1/file1
./dir1/file2
./file3
chr...@pcbsd% find . -print -o -name dir1 -prune
Same again: find stops after the -print which is always true, and ignores
the -name dir1 -and -prune.
chr...@pcbsd% find . -name * -o -name dir1 -prune
None of these primaries has a side-effect, so find rewrites this internally as
find . \( -name * -or -name dir1 -prune \) -print
-name * is always true, so find can ignore everything after the -or up to
the parenthesis. Because the first expression is true, and the parens are
followed by (an implied) -and, find has to evaluate the -print, which is
always true, so the whole expression is always true and it always prints the
name as a side-effect.
.
./test.mov
./test.mpg
./dir1
./dir1/file1
./dir1/file2
./file3
What you need is an expression with two outcomes: a -prune for some names and
a -print for others. That tells you you need an -or, and the -print must come
after it because it's always true. Before the -or, -prune is always true so
you need some sort of testing primary before the -prune.
That gives you
find . -name dir1 -prune -or -print
Jonathan
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Re: shell commands - exclusion
Jonathan McKeown wrote:
On Friday 06 February 2009 02:55, Chris Whitehouse wrote:
I think you should be able to do it with a combination of -prune and
-delete (or -exec rm -rf {} \; ) on a find command. Substitute your
other commands for rm -rf in the -exec above.
I would give you a working example except I can't figure out the syntax
for -prune. Examples from google don't seem to work in (my) FreeBSD.
[skip to the end for a simple answer without the lengthy exposition]
find(1) can be confusing, especially if you think of the ``actions''
( -print, -exec and -delete plus their variants like -ls and -ok ) as
something different from the ``tests'' ( -name and so on), or if you don't
take account of the evaluation order.
A find expression comprises a number of what the manpage calls primaries, each
of which evaluates as true or false. (It may also have a side-effect,
like -print whose side-effect is to print the name). Primaries can be
combined with -and (which is usually implied) or -or. Where -and and -or both
occur, find will group the -anded primaries together before evaluation.
Taking one of your examples below,
find . -print -or -prune -name dir1
this is grouped as
find . -print -or \( -prune -and -name dir1 \)
find will then evaluate the whole expression from left to right for each
pathname in the tree it's looking at, stopping within each set of (implied)
parentheses and within the overall expression as soon as it can determine
truth or falsehood. (This is what's referred to in programming as
short-circuiting in boolean expressions).
If primaries are linked by -and, find can stop at the first one that's false,
knowing the expression is false; if they're linked by -or it can stop at the
first one that's true, knowing the expression is true. Otherwise it has to
evaluate the whole expression.
Before it does this, though, find checks for side-effects. If there isn't a
side-effect anywhere in your expression, find will put brackets round the
whole expression and a -print after it.
Looking at your examples:
chr...@pcbsd% find .
(No expression). Find adds a -print, so this is the same as the next one:
chr...@pcbsd% find . -print
.
./test.mov
./test.mpg
./dir1
./dir1/file1
./dir1/file2
./file3
-print is always true so the expression is true for each name - they get
printed as a side-effect.
chr...@pcbsd% find . -print -o -prune dir1
find: dir1: unknown option
-prune doesn't take an argument, so dir1 is a syntax error.
chr...@pcbsd% find . -print -o -prune -name dir1
find evaluates the print, which prints each name as its side-effect. -print
evaluates as true. Since it's in an -or, find can stop there, so it never
sees the second expression ( -prune -and -name dir1: the -and is implicit).
.
./test.mov
./test.mpg
./dir1
./dir1/file1
./dir1/file2
./file3
chr...@pcbsd% find . -print -o -name dir1 -prune
Same again: find stops after the -print which is always true, and ignores
the -name dir1 -and -prune.
chr...@pcbsd% find . -name * -o -name dir1 -prune
None of these primaries has a side-effect, so find rewrites this internally as
find . \( -name * -or -name dir1 -prune \) -print
-name * is always true, so find can ignore everything after the -or up to
the parenthesis. Because the first expression is true, and the parens are
followed by (an implied) -and, find has to evaluate the -print, which is
always true, so the whole expression is always true and it always prints the
name as a side-effect.
.
./test.mov
./test.mpg
./dir1
./dir1/file1
./dir1/file2
./file3
What you need is an expression with two outcomes: a -prune for some names and
a -print for others. That tells you you need an -or, and the -print must come
after it because it's always true. Before the -or, -prune is always true so
you need some sort of testing primary before the -prune.
That gives you
find . -name dir1 -prune -or -print
Jonathan
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Thank you for this excellent answer! Now reading the man page begins to
make sense.
Chris
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Re: shell commands - exclusion
Jaime wrote:
On Wed, Feb 4, 2009 at 9:35 AM, t-u-t marshc...@gmail.com wrote:
if i have say one (or even two) single file/directories among many others,
and i want to perform any said function like cp, mv, rm, etc.. , to all
other files except that one or two, is there a way to do that in a single
command?
e.g
rm -r * {-except foo1 foo15}
I think you should be able to do it with a combination of -prune and
-delete (or -exec rm -rf {} \; ) on a find command. Substitute your
other commands for rm -rf in the -exec above.
I would give you a working example except I can't figure out the syntax
for -prune. Examples from google don't seem to work in (my) FreeBSD.
chr...@pcbsd% find .
.
./test.mov
./test.mpg
./dir1
./dir1/file1
./dir1/file2
./file3
chr...@pcbsd% find . -print
.
./test.mov
./test.mpg
./dir1
./dir1/file1
./dir1/file2
./file3
chr...@pcbsd% find . -print -o -prune dir1
find: dir1: unknown option
chr...@pcbsd% find . -print -o -prune -name dir1
.
./test.mov
./test.mpg
./dir1
./dir1/file1
./dir1/file2
./file3
chr...@pcbsd% find . -print -o -name dir1 -prune
.
./test.mov
./test.mpg
./dir1
./dir1/file1
./dir1/file2
./file3
chr...@pcbsd% find . -o -name dir1 -prune
find: -o: no expression before -o
chr...@pcbsd% find . -name * -o -name dir1 -prune
.
./test.mov
./test.mpg
./dir1
./dir1/file1
./dir1/file2
./file3
chr...@pcbsd%
(Please don't tell me to read the man page, I have several times. Even
Aeleen Frisch says it is impenetrable :P)
Chris
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Re: shell commands - exclusion
Chris Whitehouse wrote:
Jaime wrote:
On Wed, Feb 4, 2009 at 9:35 AM, t-u-t marshc...@gmail.com wrote:
if i have say one (or even two) single file/directories among many
others,
and i want to perform any said function like cp, mv, rm, etc.. , to all
other files except that one or two, is there a way to do that in a
single
command?
e.g
rm -r * {-except foo1 foo15}
I think you should be able to do it with a combination of -prune and
-delete (or -exec rm -rf {} \; ) on a find command. Substitute your
other commands for rm -rf in the -exec above.
I would give you a working example except I can't figure out the
syntax for -prune. Examples from google don't seem to work in (my)
FreeBSD.
chr...@pcbsd% find .
..
../test.mov
../test.mpg
../dir1
../dir1/file1
../dir1/file2
../file3
chr...@pcbsd% find . -print
..
../test.mov
../test.mpg
../dir1
../dir1/file1
../dir1/file2
../file3
chr...@pcbsd% find . -print -o -prune dir1
find: dir1: unknown option
chr...@pcbsd% find . -print -o -prune -name dir1
..
../test.mov
../test.mpg
../dir1
../dir1/file1
../dir1/file2
../file3
chr...@pcbsd% find . -print -o -name dir1 -prune
..
../test.mov
../test.mpg
../dir1
../dir1/file1
../dir1/file2
../file3
chr...@pcbsd% find . -o -name dir1 -prune
find: -o: no expression before -o
chr...@pcbsd% find . -name * -o -name dir1 -prune
..
../test.mov
../test.mpg
../dir1
../dir1/file1
../dir1/file2
../file3
chr...@pcbsd%
(Please don't tell me to read the man page, I have several times. Even
Aeleen Frisch says it is impenetrable :P)
Chris
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find . \! -name blah -a \! -name blah2 -delete
no?
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Re: shell commands - exclusion
On Wed, 4 Feb 2009, t-u-t wrote:
hi, i don't know if this is a freak question, but i was looking around to
see if this is possible, and what the convention would be.
if i have say one (or even two) single file/directories among many others,
and i want to perform any said function like cp, mv, rm, etc.. , to all
other files except that one or two, is there a way to do that in a single
command?
e.g
rm -r * {-except foo1 foo15}
In general this is not possible. A few commands have exclusion options, but
not many. Some shells have ways of managing glob exclusion (it's the shell
that expands wildcard patterns). Setting GLOBIGNORE works in BASH, whether
something similar works in others, you will have to investigate yourself.
But that isn't one line as you have to set GLOBIGNORE. BASH also has an
extended pattern matching option which includes negation, so you might want
to look into that.
and if there is, could the same be applied to other similar batch (?)
operations, like pkg_delete -f * { except firefox3 wine thunderbird }
etc..
pkg_delete can take regular expression arguments (see -x). Perhaps you
can devise one that will do the trick. Beware, however: it can take
multiple regular expressions and deletes package which match ANY (not all)
of them.
i'm a bit new to the shell (took me a while to figure out *ls* and *ls |
more*), but i can't find anything from google cuz i don't know what this
would be called in the first place.
Shell globbing is the operation by which the shell expands wildcards and
finds matches. What you want to do exclude things from shell globbing.
otherwise is it better to protect them with chflags or other trickery?
watch out anything involving recursion --- things can happen that you don't
expect unless you really know what you are doing.
--
Lars Eighner
http://www.larseighner.com/index.html
8800 N IH35 APT 1191 AUSTIN TX 78753-5266
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Re: shell commands - exclusion
In the last episode (Feb 04), t-u-t said:
hi, i don't know if this is a freak question, but i was looking around to
see if this is possible, and what the convention would be.
if i have say one (or even two) single file/directories among many others,
and i want to perform any said function like cp, mv, rm, etc.. , to all
other files except that one or two, is there a way to do that in a single
command?
e.g
rm -r * {-except foo1 foo15}
zsh has the ^ and ~ glob metacharacters that are enabled with you enable
EXTENDED_GLOB:
^x (Requires EXTENDED_GLOB to be set.) Matches anything except
the pattern x. This has a higher precedence than `/', so
`^foo/bar' will search directories in `.' except `./foo' for a
file named `bar'.
x~y(Requires EXTENDED_GLOB to be set.) Match anything that
matches the pattern x but does not match y. This has lower
precedence than any operator except `|', so `*/*~foo/bar' will
search for all files in all directories in `.' and then
exclude `foo/bar' if there was such a match. Multiple
patterns can be excluded by `foo~bar~baz'. In the exclusion
pattern (y), `/' and `.' are not treated specially the way
they usually are in globbing.
and if there is, could the same be applied to other similar batch (?)
operations, like pkg_delete -f * { except firefox3 wine thunderbird }
etc..
That wildcard is expanded internally by pkg_delete using the C fnmatch()
function, which just does simple *?[] shell pattern matching.
i'm a bit new to the shell (took me a while to figure out *ls* and *ls |
more*), but i can't find anything from google cuz i don't know what this
would be called in the first place.
otherwise is it better to protect them with chflags or other trickery?
One workaround is to temporarily move the files you don't want to process
into another directory, then move them back when you're done.
--
Dan Nelson
dnel...@allantgroup.com
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Re: shell commands - exclusion
On Wed, Feb 4, 2009 at 4:26 PM, Lars Eighner luvbeas...@larseighner.comwrote: In general this is not possible. A few commands have exclusion options, but not many. Some shells have ways of managing glob exclusion (it's the shell that expands wildcard patterns). Setting GLOBIGNORE works in BASH, whether something similar works in others, you will have to investigate yourself. But that isn't one line as you have to set GLOBIGNORE. BASH also has an extended pattern matching option which includes negation, so you might want to look into that. pkg_delete can take regular expression arguments (see -x). Perhaps you can devise one that will do the trick. Beware, however: it can take multiple regular expressions and deletes package which match ANY (not all) of them. Shell globbing is the operation by which the shell expands wildcards and finds matches. What you want to do exclude things from shell globbing. watch out anything involving recursion --- things can happen that you don't expect unless you really know what you are doing. thank you, i can keep to regular painstaking methods for now, but would like to get the hang of it in future;. knowing what i'm looking for now is a big step for me. thanks again ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: shell commands - exclusion
On Wed, Feb 4, 2009 at 4:48 PM, Dan Nelson dnel...@allantgroup.com wrote:
zsh has the ^ and ~ glob metacharacters that are enabled with you enable
EXTENDED_GLOB:
^x (Requires EXTENDED_GLOB to be set.) Matches anything except
the pattern x. This has a higher precedence than `/', so
`^foo/bar' will search directories in `.' except `./foo' for a
file named `bar'.
x~y(Requires EXTENDED_GLOB to be set.) Match anything that
matches the pattern x but does not match y. This has lower
precedence than any operator except `|', so `*/*~foo/bar' will
search for all files in all directories in `.' and then
exclude `foo/bar' if there was such a match. Multiple
patterns can be excluded by `foo~bar~baz'. In the exclusion
pattern (y), `/' and `.' are not treated specially the way
they usually are in globbing.
and if there is, could the same be applied to other similar batch (?)
operations, like pkg_delete -f * { except firefox3 wine thunderbird }
etc..
That wildcard is expanded internally by pkg_delete using the C fnmatch()
function, which just does simple *?[] shell pattern matching.
i'm a bit new to the shell (took me a while to figure out *ls* and *ls |
more*), but i can't find anything from google cuz i don't know what this
would be called in the first place.
otherwise is it better to protect them with chflags or other trickery?
One workaround is to temporarily move the files you don't want to process
into another directory, then move them back when you're done.
--
thank you,
i am interested in knowing how to do this stuff in general for simple
operations, since like this workaround would work fine with file
operations, but not for pkg_delete and other commands i can't think of right
now. I was just wondering if there was a commonly used/known method or
*switch* i could look into.
however, form this post i get the impression that it is better( and
worthwhile) to learn to do some proper scripting. say, prepare a list in a
file, then pass each one to the command instead of *.
cheers
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Re: shell commands - exclusion
On Wed, Feb 04, 2009 at 03:35:52PM +0100, t-u-t wrote:
hi, i don't know if this is a freak question, but i was looking around to
see if this is possible, and what the convention would be.
if i have say one (or even two) single file/directories among many others,
and i want to perform any said function like cp, mv, rm, etc.. , to all
other files except that one or two, is there a way to do that in a single
command?
e.g
rm -r * {-except foo1 foo15}
The easiest way would be to move the few files/directories you don't
want to include in your command out of the way first. :-)
and if there is, could the same be applied to other similar batch (?)
operations, like pkg_delete -f * { except firefox3 wine thunderbird }
etc..
I don't think so.
If the couple of files you don't want to rm/whatever you could try using
the find(1) command to get all the other files. The find command is a
very good tool to know.
i'm a bit new to the shell (took me a while to figure out *ls* and *ls |
more*), but i can't find anything from google cuz i don't know what this
would be called in the first place.
Maybe a stupid question, but do you know how to read manual pages?
E.g. for 'find', just enter the command 'man find' in your shell.
otherwise is it better to protect them with chflags or other trickery?
That would be my other suggestion.
Roland
--
R.F.Smith http://www.xs4all.nl/~rsmith/
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Re: shell commands - exclusion
On Wed, Feb 4, 2009 at 9:35 AM, t-u-t marshc...@gmail.com wrote:
if i have say one (or even two) single file/directories among many others,
and i want to perform any said function like cp, mv, rm, etc.. , to all
other files except that one or two, is there a way to do that in a single
command?
e.g
rm -r * {-except foo1 foo15}
I'm just shooting in the dark here, but what about this?
ls | grep -v foo1 | grep -v foo15 | xargs rm -rf
Remember the Unix pipe and the grep and xargs commands. It can
solve a lot of things by stringing together a lot of smaller commands.
I think that this might be one of those situations.
Good luck,
Jaime
--
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Tone of voice in email is misunderstood 50% of the time.
Source: http://www.howtoweb.com/cgi-bin/insider.pl?zone=214061
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Re: shell commands - exclusion
Lars Eighner wrote:
On Wed, 4 Feb 2009, t-u-t wrote:
hi, i don't know if this is a freak question, but i was looking
around to
see if this is possible, and what the convention would be.
if i have say one (or even two) single file/directories among many
others,
and i want to perform any said function like cp, mv, rm, etc.. , to all
other files except that one or two, is there a way to do that in a
single
command?
e.g
rm -r * {-except foo1 foo15}
In general this is not possible. . . .
Oh yes it is, it is very easy. I've done things like this in unix
environments for years. I also apply it to tar commands all the time.
All you have to do is this:
$ ls rm.in
$ vi rm.in
. . . edit out all the files you don't want to erase . . .
$ rm `cat rm.in`
-Will
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