From d6675522451b73a530d4529e027134d886ccd550 Mon Sep 17 00:00:00 2001 From: Jim Meyering Date: Fri, 14 May 2004 07:32:56 +0000 Subject: [PATCH] (sort invocation): Document that "sort -m -o F" might write F before reading all the input. --- doc/coreutils.texi | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/doc/coreutils.texi b/doc/coreutils.texi index ead568b1d6..5e5b8d17a7 100644 --- a/doc/coreutils.texi +++ b/doc/coreutils.texi @@ -3265,9 +3265,13 @@ starting with 1. So to sort on the second field, you'd use @opindex --output @cindex overwriting of input, allowed Write output to @var{output-file} instead of standard output. -If necessary, @command{sort} reads input before opening +Normally, @command{sort} reads all input before opening @var{output-file}, so you can safely sort a file in place by using commands like @code{sort -o F F} and @code{cat F | sort -o F}. +However, @command{sort} with @option{--merge} (@option{-m}) can open +the output file before reading all input, so a command like @code{cat +F | sort -m -o F - G} is not safe as @command{sort} might start +writing @file{F} before @command{cat} is done reading it. @vindex POSIXLY_CORRECT On newer systems, @option{-o} cannot appear after an input file if -- 2.47.3