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<A NAME="PAGENUM-253"><P>Page 253</P></A>
<P><B>
DESCRIPTION
</B></P>
<P>The gzexe utility enables you to compress executables in place and have them automatically uncompress and execute
when you run them (at a penalty in performance). For example if you execute
gzexe /bin/cat, it will create the following two FILES:
</P>
<!-- CODE SNIP //-->
<PRE>
-r-xr-xr-x 1 root bin 9644 Feb 11 11:16 /bin/cat
-r-xr-xr-x 1 bin bin 24576 Nov 23 13:21 /bin/cat~
</PRE>
<!-- END CODE SNIP //-->
<P>/bin/cat~ is the original file and /bin/cat is the self-uncompressing executable file. You can remove
/bin/cat~ when you are sure that /bin/cat works properly.
</P>
<P>This utility is most useful on systems with very small disks.
</P>
<P><B>
OPTIONS
</B></P>
<TABLE>
<TR><TD>
_d
</TD><TD>
Decompress the given executables instead of compressing them
</TD></TR></TABLE>
<P><B>
SEE ALSO
</B></P>
<P>gzip(1), znew(1), zmore(1), zcmp(1), zforce(1)
</P>
<P><B>
CAVEATS
</B></P>
<P>The compressed executable is a shell script. This may create some security holes. In particular, the compressed
executable relies on the PATH ENVIRONMENT variable to find
gzip and some other utilities (tail, chmod, ln,
sleep).
</P>
<P><B>
BUGS
</B></P>
<P>gzexe attempts to retain the original file attributes on the compressed executable, but you may have to fix them manually
in some cases, using chmod or chown.
</P>
<H3><A NAME="ch01_ 109">
head
</A></H3>
<P>head—Output the first part of FILES
</P>
<P><B>
SYNOPSIS
</B></P>
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<PRE>
head [_c N[bkm]] [_n N] [_qv] [--bytes=N[bkm]] [--lines=N] [--quiet] [--silent]
[--verbose] [--help] [--version] [file...]
head [_Nbcklmqv] [file...]
</PRE>
<!-- END CODE SNIP //-->
<P><B>
DESCRIPTION
</B></P>
<P>This manual page documents the GNU version of
head. head prints the first part (10 lines by default) of each given file;
it reads from standard input if no FILES are given or when a filename of
_ is encountered. If more than one file is given, it
prints a header consisting of the file's name enclosed in
==> and <== before the output for each file.
</P>
<P><B>
OPTIONS
</B></P>
<P>head accepts two option FORMATS: the new one, in which numbers are arguments to the option letters; and the old one,
in which the number precedes any option letters.
</P>
<TABLE>
<TR><TD>
_c N, --bytes N
</TD><TD>
Print first N bytes. N is a nonzero integer, optionally followed by one of the following characters
to specify a different unit.
</TD></TR></TABLE>
<TBL>
<COLS=3>
<C>
<C>
b
<C>
512-byte blocks.
<C>
<C>
k
<C>
1-kilobyte blocks.
<C>
<C>
m
<C>
1-megabyte blocks.
<TBL>
<COLS=2>
<C>
_l, _n N, --lines N
<C>
Print first N lines.
<C>
_q, --quiet, --silent
<C>
Never print filename headers.
<A NAME="PAGENUM-254"><P>Page 254</P></A>
<TABLE>
<TR><TD>
_v, --verbose
</TD><TD>
Always print filename headers.
</TD></TR><TR><TD>
--help
</TD><TD>
Print a usage message and exit with a nonzero status.
</TD></TR><TR><TD>
--version
</TD><TD>
Print version information on standard output, then exit.
</TD></TR></TABLE>
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<P>
GNU Text Utilities
</P>
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<H3><A NAME="ch01_ 110">
hexdump
</A></H3>
<P>hexdump—ASCII, decimal, hexadecimal, octal dump
</P>
<P><B>
SYNOPSIS
</B></P>
<!-- CODE SNIP //-->
<PRE>
hexdump [-bcdovx] [-e format_string] [-f format_file] [-n length] [-s skip] [file ...]
</PRE>
<!-- END CODE SNIP //-->
<P><B>
DESCRIPTION
</B></P>
<P>The hexdump utility is a filter that displays the specified FILES, or the standard input, if no FILES are specified, in a
user-specified format.
</P>
<P>The OPTIONS are as follows:
</P>
<TABLE>
<TR><TD>
-b
</TD><TD>
One-byte octal display. Display the input offset in hexadecimal, followed by sixteen
space-separated, three-column, zero-filled bytes of input data, in octal, per line.
</TD></TR><TR><TD>
-c
</TD><TD>
One-byte character display. Display the input offset in hexadecimal, followed by sixteen
space-separated, three-column, space-filled, characters of input data per line.
</TD></TR><TR><TD>
-d
</TD><TD>
Two-byte decimal display. Display the input offset in hexadecimal, followed by eight
space-separated, five-column, zero-filled, two-byte units of input data, in unsigned decimal, per line.
</TD></TR><TR><TD>
-e format_string
</TD><TD>
Specify a format string to be used for displaying data.
</TD></TR><TR><TD>
-f format_file
</TD><TD>
Specify a file that contains one or more newline separated format strings. Empty lines and
lines whose first nonblank character is a hash mark
(#) are ignored.
</TD></TR><TR><TD>
-n length
</TD><TD>
Interpret only length bytes of input.
</TD></TR><TR><TD>
-o
</TD><TD>
Two-byte octal display. Display the input offset in hexadecimal, followed by eight
space-separated, six-column, zero-filled, two-byte quantities of input data, in octal, per line.
</TD></TR><TR><TD>
-s offset
</TD><TD>
Skip offset bytes from the beginning of the input. By default,
offset is interpreted as a decimal number. With a leading
0x or 0X, offset is interpreted as a hexadecimal number; otherwise, with
a leading 0, offset is interpreted as an octal number. Appending the character
b, k, or m to offset causes it to be interpreted as a multiple of 512, 1024, or 1048576, respectively.
</TD></TR><TR><TD>
-v
</TD><TD>
The -v option causes hexdump to display all input data. Without the
-v option, any number of groups of output lines, which would be identical to the immediately preceding group of
output lines (except for the input offsets), are replaced with a line comprised of a single asterisk.
</TD></TR><TR><TD>
-x
</TD><TD>
Two-byte hexadecimal display. Display the input
offset in hexadecimal, followed by eight, space-separated, four-column, zero-filled, two-byte quantities of input data, in hexadecimal, per line.
</TD></TR></TABLE>
<P>For each input file, hexdump sequentially copies the input to standard output, transforming the data according to the
format strings specified by the -e and -f OPTIONS, in the order that they were specified.
</P>
<P><B>
FORMATS
</B></P>
<P>A format string contains any number of format units, separated by whitespace. A format unit contains up to three items:
an iteration count, a byte count, and a format.
</P>
<P>The iteration count is an optional positive integer, which defaults to one. Each format is applied iteration count times.
</P>
<P>The byte count is an optional positive integer. If specified, it defines the number of bytes to be interpreted by each
iteration of the format.
</P>
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