diff options
| -rw-r--r-- | doc/coreutils.texi | 87 |
1 files changed, 35 insertions, 52 deletions
diff --git a/doc/coreutils.texi b/doc/coreutils.texi index e3311681e..983a69411 100644 --- a/doc/coreutils.texi +++ b/doc/coreutils.texi @@ -1835,7 +1835,7 @@ Output at most @var{bytes} bytes of the input. Prefixes and suffixes on @cindex string constants, outputting Instead of the normal output, output only @dfn{string constants}: at least @var{bytes} consecutive @acronym{ASCII} graphic characters, -followed by a null (zero) byte. +followed by a zero byte (@acronym{ASCII} @sc{nul}). Prefixes and suffixes on @code{bytes} are interpreted as for the @option{-j} option. @@ -1874,7 +1874,7 @@ hexadecimal @end table The type @code{a} outputs things like @samp{sp} for space, @samp{nl} for -newline, and @samp{nul} for a null (zero) byte. Only the least significant +newline, and @samp{nul} for a zero byte. Only the least significant seven bits of each byte is used; the high-order bit is ignored. Type @code{c} outputs @samp{ }, @samp{\n}, and @code{\0}, respectively. @@ -3267,16 +3267,17 @@ Print only the maximum line lengths. @c texi2dvi (GNU Texinfo 4.11) 1.104 @c @cindex including files from @command{\cmd\} Disallow processing files named on the command line, and instead process -those named in file @var{file}; each name being terminated by a @sc{nul} byte. +those named in file @var{file}; each name being terminated by a zero byte +(@acronym{ASCII} @sc{nul}). This is useful \withTotalOption\ when the list of file names is so long that it may exceed a command line length limitation. In such cases, running @command{\cmd\} via @command{xargs} is undesirable because it splits the list into pieces and makes @command{\cmd\} print \subListOutput\ for each sublist rather than for the entire list. -One way to produce a list of @sc{nul} terminated file names is with @sc{gnu} +One way to produce a list of @acronym{ASCII} @sc{nul} terminated file names is with @sc{gnu} @command{find}, using its @option{-print0} predicate. -If @var{file} is @samp{-} then the @sc{nul} terminated file names +If @var{file} is @samp{-} then the @acronym{ASCII} @sc{nul} terminated file names are read from standard input. @end macro @filesZeroFromOption{wc,,a total} @@ -4003,9 +4004,8 @@ However, fields that extend to the end of the line, as @option{-k 2}, or fields consisting of a range, as @option{-k 2,3}, retain the field separators present between the endpoints of the range. -To specify a null character (@acronym{ASCII} @sc{nul}) as -the field separator, use the two-character string @samp{\0}, e.g., -@samp{sort -t '\0'}. +To specify @acronym{ASCII} @sc{nul} as the field separator, +use the two-character string @samp{\0}, e.g., @samp{sort -t '\0'}. @item -T @var{tempdir} @itemx --temporary-directory=@var{tempdir} @@ -4038,18 +4038,21 @@ For example, @code{sort -n -u} inspects only the value of the initial numeric string when checking for uniqueness, whereas @code{sort -n | uniq} inspects the entire line. @xref{uniq invocation}. +@macro zeroTerminatedOption @item -z @itemx --zero-terminated @opindex -z @opindex --zero-terminated -@cindex sort zero-terminated lines -Treat the input as a set of lines, each terminated by a null character -(@acronym{ASCII} @sc{nul}) instead of a line feed -(@acronym{ASCII} @sc{lf}). +@cindex process zero-terminated items +Delimit items with a zero byte rather than a newline (@acronym{ASCII} @sc{lf}). +I.E. treat input as items separated by @acronym{ASCII} @sc{nul} +and terminate output items with @acronym{ASCII} @sc{nul}. This option can be useful in conjunction with @samp{perl -0} or @samp{find -print0} and @samp{xargs -0} which do the same in order to reliably handle arbitrary file names (even those containing blanks or other special characters). +@end macro +@zeroTerminatedOption @end table @@ -4297,18 +4300,7 @@ commands like @code{shuf -o F <F} and @code{cat F | shuf -o F}. Use @var{file} as a source of random data used to determine which permutation to generate. @xref{Random sources}. -@item -z -@itemx --zero-terminated -@opindex -z -@opindex --zero-terminated -@cindex sort zero-terminated lines -Treat the input and output as a set of lines, each terminated by a zero byte -(@acronym{ASCII} @sc{nul} (Null) character) instead of an -@acronym{ASCII} @sc{lf} (Line Feed). -This option can be useful in conjunction with @samp{perl -0} or -@samp{find -print0} and @samp{xargs -0} which do the same in order to -reliably handle arbitrary file names (even those containing blanks -or other special characters). +@zeroTerminatedOption @end table @@ -4476,13 +4468,13 @@ This is equivalent to @option{--all-repeated} (@option{-D}). @item prepend Output a newline before each group of repeated lines. -With @option{--zero-terminated} (@option{-z}), use -an @acronym{ASCII} @sc{nul} (zero) byte instead of a newline. +With @option{--zero-terminated} (@option{-z}), use a zero +byte (@acronym{ASCII} @sc{nul}) instead of a newline. @item separate Separate groups of repeated lines with a single newline. -With @option{--zero-terminated} (@option{-z}), use -an @acronym{ASCII} @sc{nul} (zero) byte instead of a newline. +With @option{--zero-terminated} (@option{-z}), use a zero +byte (@acronym{ASCII} @sc{nul}) instead of a newline. This is the same as using @samp{prepend}, except that no delimiter is inserted before the first group, and hence may be better suited for output direct to users. @@ -4512,18 +4504,7 @@ Compare at most @var{n} characters on each line (after skipping any specified fields and characters). By default the entire rest of the lines are compared. -@item -z -@itemx --zero-terminated -@opindex -z -@opindex --zero-terminated -@cindex sort zero-terminated lines -Treat the input as a set of lines, each terminated by a null character -(@acronym{ASCII} @sc{nul}) instead of a line feed -(@acronym{ASCII} @sc{lf}). -This option can be useful in conjunction with @samp{sort -z}, @samp{perl -0} or -@samp{find -print0} and @samp{xargs -0} which do the same in order to -reliably handle arbitrary file names (even those containing blanks -or other special characters). +@zeroTerminatedOption @end table @@ -5032,10 +5013,10 @@ disabled, width of references is not taken into account in the output line width computations. @item -All 256 bytes, even null bytes, are always read and processed from -input file with no adverse effect, even if @sc{gnu} extensions are disabled. -However, System V @command{ptx} does not accept 8-bit characters, a few -control characters are rejected, and the tilde @kbd{~} is also rejected. +All 256 bytes, even @acronym{ASCII} @sc{nul} bytes, are always read and +processed from input file with no adverse effect, even if @sc{gnu} extensions +are disabled. However, System V @command{ptx} does not accept 8-bit characters, +a few control characters are rejected, and the tilde @kbd{~} is also rejected. @item Input line length is only limited by available memory, even if @sc{gnu} @@ -7704,7 +7685,7 @@ The @samp{excl} and @samp{nocreat} conversions are mutually exclusive. Do not truncate the output file. @item sync -@opindex sync @r{(padding with nulls)} +@opindex sync @r{(padding with @acronym{ASCII} @sc{nul}s)} Pad every input block to size of @samp{ibs} with trailing zero bytes. When used with @samp{block} or @samp{unblock}, pad with spaces instead of zero bytes. @@ -10091,9 +10072,10 @@ is at level 0, so @code{du --max-depth=0} is equivalent to @code{du -s}. @itemx --null @opindex --null @cindex output null-byte-terminated lines -Output a null byte at the end of each line, rather than a newline. -This option enables other programs to parse the output of @command{du} -even when that output would contain file names with embedded newlines. +Output a zero byte (@acronym{ASCII} @sc{nul}) at the end of each line, +rather than a newline. This option enables other programs to parse the +output of @command{du} even when that output would contain file names +with embedded newlines. @optSi @@ -10508,7 +10490,7 @@ produce no further output @item \f form feed @item \n -new line +newline @item \r carriage return @item \t @@ -12070,7 +12052,8 @@ May be negated. @item ofdel @opindex ofdel @cindex pad character -Use delete characters for fill instead of null characters. Non-@acronym{POSIX}. +Use @acronym{ASCII} @sc{del} characters for fill instead of +@acronym{ASCII} @sc{nul} characters. Non-@acronym{POSIX}. May be negated. @item nl1 @@ -14036,8 +14019,8 @@ These operands are evaluated left-to-right, so if two operands mention the same variable the earlier is ignored. Environment variable names can be empty, and can contain any -characters other than @samp{=} and the null character (@acronym{ASCII} -@sc{nul}). However, it is wise to limit yourself to names that +characters other than @samp{=} and @acronym{ASCII} @sc{nul}. +However, it is wise to limit yourself to names that consist solely of underscores, digits, and @acronym{ASCII} letters, and that begin with a non-digit, as applications like the shell do not work well with other names. |