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[PATCH 3/3] doc: document split's new --filter=CMD option
From: |
Jim Meyering |
Subject: |
[PATCH 3/3] doc: document split's new --filter=CMD option |
Date: |
Tue, 3 May 2011 10:54:12 +0200 |
From: Jim Meyering <address@hidden>
* doc/coreutils.texi (split invocation): Describe --filter=CMD.
* NEWS (New feature): Mention it.
---
NEWS | 10 ++++++++++
doc/coreutils.texi | 23 +++++++++++++++++++++--
2 files changed, 31 insertions(+), 2 deletions(-)
diff --git a/NEWS b/NEWS
index c90e02f..82ce53c 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,16 @@ GNU coreutils NEWS -*-
outline -*-
* Noteworthy changes in release ?.? (????-??-??) [?]
+** New features
+
+ split accepts a new --filter=CMD option. With it, split filters output
+ through CMD. CMD may use the $FILE environment variable, which is set to
+ the nominal output file name for each invocation of CMD. For example, to
+ split a file into 3 approximately equal parts, which are then compressed:
+ split -n3 --filter='xz > $FILE.xz' big
+ Note the use of single quotes, not double quotes.
+ That creates files named xaa.xz, xab.xz and xac.xz.
+
* Noteworthy changes in release 8.12 (2011-04-26) [stable]
diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index d2377f4..457ecab 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -2992,8 +2992,8 @@ split invocation
Put @var{lines} lines of @var{input} into each output file.
For compatibility @command{split} also supports an obsolete
-option syntax @option{-@var{lines}}. New scripts should use @option{-l
-@var{lines}} instead.
+option syntax @option{-@var{lines}}. New scripts should use
+@option{-l @var{lines}} instead.
@item -b @var{size}
@itemx --bytes=@var{size}
@@ -3011,6 +3011,25 @@ split invocation
@var{size} bytes are broken into multiple files.
@var{size} has the same format as for the @option{--bytes} option.
+@itemx --filter=@var{command}
+@opindex --filter
+With this option, rather than simply writing to each output file,
+write through a pipe to the specified shell @var{command} for each output file.
+@var{command} should use the $FILE environment variable, which is set
+to a different output file name for each invocation of the command.
+For example, imagine that you have a 1TiB compressed file
+that, if uncompressed, would be too large to reside on disk,
+yet you must split it into individually-compressed pieces
+of a more manageable size.
+To do that, you might run this command:
+
+@example
+xz -dc BIG.xz | split -b200G --filter='xz > $FILE.xz' - big-
+@end example
+
+Assuming a 10:1 compression ratio, that would create about fifty 20GiB files
+with names @file{big-xaa.xz}, @file{big-xab.xz}, @file{big-xac.xz}, etc.
+
@item -n @var{chunks}
@itemx --number=@var{chunks}
@opindex -n
--
1.7.5.141.g791a