2007-07-01 James Youngman <[EMAIL PROTECTED]>
* doc/find.texi (Copying A Subset of Files): Added a new worked
example.
---
NEWS | 1 +
doc/find.texi | 47 ++++++++++++++++++++++++++++++++++++++++++++---
2 files changed, 45 insertions(+), 3 deletions(-)
diff --git a/NEWS b/NEWS
index ac8bef1..362c38a 100644
--- a/NEWS
+++ b/NEWS
@@ -29,6 +29,7 @@ recent findutils release first.
Introduced doc/find-maint.texi, a maintenance manual for findutils.
+Added an extra worked example for find (copying a subset of files).
* Major changes in release 4.3.8
diff --git a/doc/find.texi b/doc/find.texi
index 3efc276..113f82e 100644
--- a/doc/find.texi
+++ b/doc/find.texi
@@ -3807,9 +3807,9 @@ performed, and compares the different ways of achieving
them.
@menu
* Deleting Files::
+* Copying A Subset of Files::
* Updating A Timestamp File::
@end menu
[EMAIL PROTECTED] * Copying A Subset of Files::
@node Deleting Files
@section Deleting Files
@@ -4150,8 +4150,49 @@ portable. The most efficient portable alternative is
@samp{-exec
@dots{}+}, but this is insecure and isn't supported by versions of GNU
findutils prior to 4.2.12.
[EMAIL PROTECTED] @node Copying A Subset of Files
[EMAIL PROTECTED] @section Copying A Subset of Files
[EMAIL PROTECTED] Copying A Subset of Files
[EMAIL PROTECTED] Copying A Subset of Files
+
+Suppose you want to copy some files from @file{/source-dir} to
[EMAIL PROTECTED]/dest-dir}, but there are a small number of files in
[EMAIL PROTECTED]/source-dir} you don't want to copy.
+
+One option of course is @code{cp /source-dir /dest-dir} followed by
+deletion of the unwanted material under @file{/dest-dir}. But often
+that can be inconvenient, because for example we would have copied a
+large amount of extraneous material, or because @file{/dest-dir} is
+too small. Naturally there are many other possible reasons why this
+strategy may be unsuitable.
+
+So we need to have some way of identifying which files we want to
+copy, and we need to have a way of copying that file list. The second
+part of this condition is met by @code{cpio -p}. Of course, we can
+identify the files we wish to copy by using @code{find}. Here is a
+command that solves our problem:
+
[EMAIL PROTECTED]
+cd /source-dir
+find . -name '.snapshot' -prune -o \( \! -name '*~' -print0 \) |
+cpio -pmd0 /dest-dir
[EMAIL PROTECTED] example
+
+The first part of the @code{find} command here identifies files or
+directoires named @file{.snapshot} and tells @code{find} not to
+recurse into them (since they do not need to be copied). The
+combination @code{-name '.snapshot' -prune} yields false for anything
+that didn't get pruned, but it is exactly those files we want to
+copy. Therefore we need to use an OR (@samp{-o}) condition to
+introduce the rest of our expression. The remainder of the expression
+simply arranges for the name of any file not ending in @samp{~} to be
+printed.
+
+Using @code{-print0} ensures that white space characters in file names
+do not pose a problem. The @code{cpio} command does the actual work
+of copying files. The program as a whole fails if the @code{cpio}
+program returns nonzero. If the @code{find} command returns non-zero
+on the other hand, the Unix shell will not diagnose a problem (since
[EMAIL PROTECTED] is not the last command in the pipeline).
+
@node Updating A Timestamp File
@section Updating A Timestamp File
--
1.5.2.1
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