Como as respostas do @ slm vão para as origens e possíveis razões, não repetirei isso aqui. Essa opção não está na lista de recursos rejeitados do coreutils , mas o patch abaixo agora é rejeitado por Pádraig Brady após enviá-lo para a lista de discussão do coreutils. Pela resposta, fica claro que essa é uma razão filosófica (a lsprodução é para consumo humano).
Se você quiser experimentar se essa opção é razoável, faça o seguinte:
git clone git://git.sv.gnu.org/coreutils
cd coreutils
./bootstrap
./configure
make
em seguida, aplique o seguinte patch ao commit b938b6e289ef78815935ffa705673a6a8b2ee98e dd 2014-01-29:
From 6413d5e2a488ecadb8b988c802fe0a5e5cb7d8f4 Mon Sep 17 00:00:00 2001
From: Anthon van der Neut <address@hidden>
Date: Mon, 3 Feb 2014 15:33:50 +0100
Subject: [PATCH] ls: adding --zero/-z option, including tests
* src/ls.c has the necessary changes to allow -z/--zero option to be
specified, resulting in a NUL seperated list of files. This
allows the output of e.g. "ls -rtz" to be piped into other programs
* tests/ls/no-args.sh was extended to test the -z option
* test/ls/rt-zero.sh was added to test both the long and short option
together with "-t"
This patch was inspired by numerous questions on unix.stackexchange.com
where the output of ls was piped into some other program, invariably
resulting in someone pointing out that is an unsafe practise because of
possible newlines and other characters in the filenames.
---
src/ls.c | 31 +++++++++++++++++++++++++------
tests/ls/no-arg.sh | 7 ++++++-
tests/ls/rt-zero.sh | 38 ++++++++++++++++++++++++++++++++++++++
3 files changed, 69 insertions(+), 7 deletions(-)
create mode 100755 tests/ls/rt-zero.sh
diff --git a/src/ls.c b/src/ls.c
index 5d87dd3..962e6bb 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -381,6 +381,7 @@ static int file_size_width;
many_per_line for just names, many per line, sorted vertically.
horizontal for just names, many per line, sorted horizontally.
with_commas for just names, many per line, separated by commas.
+ with_zero for just names, one per line, separated by NUL.
-l (and other options that imply -l), -1, -C, -x and -m control
this parameter. */
@@ -391,7 +392,8 @@ enum format
one_per_line, /* -1 */
many_per_line, /* -C */
horizontal, /* -x */
- with_commas /* -m */
+ with_commas, /* -m */
+ with_zero, /* -z */
};
static enum format format;
@@ -842,6 +844,7 @@ static struct option const long_options[] =
{"block-size", required_argument, NULL, BLOCK_SIZE_OPTION},
{"context", no_argument, 0, 'Z'},
{"author", no_argument, NULL, AUTHOR_OPTION},
+ {"zero", no_argument, NULL, 'z'},
{GETOPT_HELP_OPTION_DECL},
{GETOPT_VERSION_OPTION_DECL},
{NULL, 0, NULL, 0}
@@ -850,12 +853,12 @@ static struct option const long_options[] =
static char const *const format_args[] =
{
"verbose", "long", "commas", "horizontal", "across",
- "vertical", "single-column", NULL
+ "vertical", "single-column", "zero", NULL
};
static enum format const format_types[] =
{
long_format, long_format, with_commas, horizontal, horizontal,
- many_per_line, one_per_line
+ many_per_line, one_per_line, with_zero
};
ARGMATCH_VERIFY (format_args, format_types);
@@ -1645,7 +1648,7 @@ decode_switches (int argc, char **argv)
{
int oi = -1;
int c = getopt_long (argc, argv,
- "abcdfghiklmnopqrstuvw:xABCDFGHI:LNQRST:UXZ1",
+ "abcdfghiklmnopqrstuvw:xzABCDFGHI:LNQRST:UXZ1",
long_options, &oi);
if (c == -1)
break;
@@ -1852,6 +1855,10 @@ decode_switches (int argc, char **argv)
format = one_per_line;
break;
+ case 'z':
+ format = with_zero;
+ break;
+
case AUTHOR_OPTION:
print_author = true;
break;
@@ -2607,7 +2614,8 @@ print_dir (char const *name, char const *realname, bool
command_line_arg)
ls uses constant memory while processing the entries of
this directory. Useful when there are many (millions)
of entries in a directory. */
- if (format == one_per_line && sort_type == sort_none
+ if ((format == one_per_line || format == with_zero)
+ && sort_type == sort_none
&& !print_block_size && !recursive)
{
/* We must call sort_files in spite of
@@ -3598,6 +3606,14 @@ print_current_files (void)
}
break;
+ case with_zero:
+ for (i = 0; i < cwd_n_used; i++)
+ {
+ print_file_name_and_frills (sorted_file[i], 0);
+ putchar ('\0');
+ }
+ break;
+
case many_per_line:
print_many_per_line ();
break;
@@ -4490,6 +4506,7 @@ print_many_per_line (void)
indent (pos + name_length, pos + max_name_length);
pos += max_name_length;
}
+ putchar ('X'); // AvdN
putchar ('\n');
}
}
@@ -4780,7 +4797,8 @@ Sort entries alphabetically if none of -cftuvSUX nor
--sort is specified.\n\
-F, --classify append indicator (one of */=>@|) to entries\n\
--file-type likewise, except do not append '*'\n\
--format=WORD across -x, commas -m, horizontal -x, long -l,\n\
- single-column -1, verbose -l, vertical -C\n\
+ single-column -1, verbose -l, vertical -C,\n\
+ zeros -z\n\
--full-time like -l --time-style=full-iso\n\
"), stdout);
fputs (_("\
@@ -4888,6 +4906,7 @@ Sort entries alphabetically if none of -cftuvSUX nor
--sort is specified.\n\
-X sort alphabetically by entry extension\n\
-Z, --context print any security context of each file\n\
-1 list one file per line\n\
+ -z, --zero list files separated with NUL\n\
"), stdout);
fputs (HELP_OPTION_DESCRIPTION, stdout);
fputs (VERSION_OPTION_DESCRIPTION, stdout);
diff --git a/tests/ls/no-arg.sh b/tests/ls/no-arg.sh
index e356a29..da28b96 100755
--- a/tests/ls/no-arg.sh
+++ b/tests/ls/no-arg.sh
@@ -30,11 +30,16 @@ out
symlink
EOF
-
ls -1 > out || fail=1
compare exp out || fail=1 +/bin/echo -en "dir\00exp\00out\00symlink\00" > exp || framework_failure_
+
+ls --zero > out || fail=1
+
+compare exp out || fail=1
+
cat > exp <<\EOF
.:
dir
diff --git a/tests/ls/rt-zero.sh b/tests/ls/rt-zero.sh
new file mode 100755
index 0000000..cdbd311
--- /dev/null
+++ b/tests/ls/rt-zero.sh
@@ -0,0 +1,38 @@
+#!/bin/sh
+# Make sure name is used as secondary key when sorting on mtime or ctime.
+
+# Copyright (C) 1998-2014 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
+print_ver_ ls touch
+
+date=1998-01-15
+
+touch -d "$date" c || framework_failure_
+touch -d "$date" a || framework_failure_
+touch -d "$date" b || framework_failure_
+
+
+ls -zt a b c > out || fail=1
+/bin/echo -en "a\00b\00c\00" > exp
+compare exp out || fail=1
+
+rm -rf out exp
+ls -rt --zero a b c > out || fail=1
+/bin/echo -en "c\00b\00a\00" > exp
+compare exp out || fail=1
+
+Exit $fail
--
1.7.9.5
Depois de outro make, você pode testá-lo com:
src/ls -rtz | xargs -0 -n1 src/ls -ld
Portanto, o patch funciona e não vejo uma razão para isso, mas isso não é prova de que não há razão técnica para deixar de fora a opção. ls -R0pode não fazer muito sentido, mas também o ls -Rmque lspode ser feito imediatamente.