dump strings in pointer order
see also :
[-iorsx] [-c char]
unstr [-c char]
add an example, a script, a trick and tips
no example yet ...
... Feel free to add your own example above to help other Linux-lovers !
reads a file containing groups of lines separated by a line
containing a single percent ’%’ sign (or other
specified delimiter character) and creates a data file which
contains a header structure and a table of file offsets for
each group of lines. This allows random access of the
file, if not specified on the command line, is named
The purpose of
unstr is to undo the work of strfile. It
prints out the strings contained in the sourcefile, which is
datafile.ext without its extension, or
datafile if no extension is specified (in this case,
the extension .dat is added to the name of the
datafile) in the order that they are listed in the header
file datafile. If no outputfile is specified,
it prints to standard output; otherwise it prints to the
file specified. unstr can also universally change the
delimiter character in a strings file. It is possible to
create sorted versions of input files by using strfile
-o and then using unstr to dump them out in
the table order.
The options are as follows:
Change the delimiting character
from the percent sign to char. This option is
available for both strfile and unstr.
Ignore case when ordering the strings.
Order the strings in alphabetical order. The offset
table will be sorted in the alphabetical order of the groups
of lines referenced. Any initial non-alphanumeric characters
are ignored. This option causes the STR_ORDERED bit in the
header str_flags field to be set. (It also now really
does sort! It didn’t used to).
Randomize access to the strings. Entries in the offset
table will be randomly ordered. This option causes the
STR_RANDOM bit in the header str_flags field to be
set. (And really does randomize)
Run silently; don’t give a summary message when
Note that each alphabetic character in the groups of
lines is rotated 13 positions in a simple caesar cypher.
This option causes the STR_ROTATED bit in the header
str_flags field to be set. Note that it does
not rotate the strings--that operation must be performed
The format of the header is:
unsigned long str_version; /* version number */
unsigned long str_numstr; /* # of strings in the file */
unsigned long str_longlen; /* length of longest string */
unsigned long str_shortlen; /* shortest string length */
#define STR_RANDOM 0x1 /* randomized pointers */
#define STR_ORDERED 0x2 /* ordered pointers */
#define STR_ROTATED 0x4 /* rot-13’d text */
unsigned long str_flags; /* bit field for flags */
char str_delim; /* delimiting character */
All fields are
written in network byte order.
What can you do with this besides printing sarcastic and obscene
messages to the screens of lusers at login or logout?
There are some other possibilities. Source code for a
sample program, randstr, is included with this
distribution: randstr splits the difference between unstr
and fortune. It reads a single, specified file, and
randomly selects a single text string.
Include strfile.h into a news reading/posting program, to
generate random signatures. Tin(1) does something similar,
in a much more complex manner.
Include it in a game. While strfile doesn’t support
’fields’ or ’records’, there’s no
reason that the text strings can’t be consistent: first
line, a die roll; second line, a score; third and subsequent
lines, a text message.
Use it to store your address book. Hell, some of the guys I know
would be as well off using it to decide who to call on Friday
nights (and for some, it wouldn’t matter whether there were
phone numbers in it or not).
Use it in ’lottery’ situations. If you’re an
ISP, write a script to store login names and GECOS from
/etc/passwd in strfile format, write another to send
’congratulations, you’ve won’ to the lucky
login selected. The prize might be a month’s free service,
or if you’re AOL, a month free on a real service provider.
Fewer now, one
hopes. However, fortunes (text strings) beginning with a
blank line appear to be sorted between random letters. This
includes ASCII art that contains no letters, and first lines
that are solely non-alphanumeric, apparently. I’ve no
idea why this should be.
strfile utility first appeared in 4.4BSD. This
version was heavily modified, much of it in ways peculiar to
Linux. Work has since been done to make the code more
generic, and has so far been tested to work with SunOS 4.x.
More platforms are expected to be supported as work