STRFILE(1)

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🦋 STRFILE(1) — the random-access-string-maker, bestie edition 💅

Okay so real talk, this one's a classic from the 4th Berkeley Distribution and it's giving vintage but still iconic. We're talking strfile and its bestie unstr — two little utilities that just want to help you organize your strings, no cap. Let's get into it ✨

🌸 NAME 🌸

strfile — creates a random access file for storing strings (yes bestie, it's the main character)

unstr — dumps strings in pointer order (the loyal sidekick that undoes the magic 🫶)

🌈 SYNOPSIS 🌈

              strfile     [-iorsx]
                 [-c char]
                 sourcefile
                 [outputfile]

            unstr     [-c char]
               datafile.[ext]
               [outputfile]

💖 DESCRIPTION 💖

Okay so listen. strfile reads a file that's full of groups of lines — each group separated by a line containing just a single percent % sign (or whatever delimiter char you're feeling that day). Then it creates a data file containing a header structure and a table of file offsets for each group of lines. This is literally what allows random access of the strings. Slay. 🔥

The output file — if you don't specify one on the command line — gets named sourcefile.dat. Default naming, we love to see it.

Now unstr's whole personality is undoing what strfile did. It prints out the strings contained in the sourcefile, which is datafile.ext without its extension, or datafile if no extension is specified (in that case, the extension .dat is added to the name of the datafile) — in the order that they're listed in the header file datafile. If no outputfile is specified, it prints to standard output; otherwise it prints to the file specified. Versatile queen. 👑

Fun fact: unstr can also universally change the delimiter character in a strings file. And get this — it's 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 workflow is giving organized chaos and I'm obsessed.

✨ OPTIONS ✨

The options are as follows, bestie — pay attention:

  • -c char — Change the delimiting character from the percent sign to char. This option is available for both strfile and unstr. So flexible, so iconic.
  • -i — Ignore case when ordering the strings. Case-sensitive? Not today, bestie. 🙈
  • -o — 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. Character development, honestly.) 💀
  • -r — 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. Unlike some flags we could mention.) 🎲
  • -s — Run silently; don't give a summary message when finished. Quiet luxury, no notes. 🎀
  • -x — 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 separately. Important distinction, babes. Don't come for me. 🌸

The format of the header is literally this, and you're gonna want to screenshot it for later:

#define VERSION 1
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 */

And the vibe check on this header? All fields are written in network byte order. Periodt. 🌐

💀 BUGS 💀

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. Genuinely no clue, bestie — it's giving mystery. 😭

🔥 OTHER USES 🔥

What can you do with this besides printing sarcastic and obscene messages to the screens of lusers at login or logout? (Okay, valid question — but we're not judging anyone's hobbies here. 🙈)

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.

  1. Include strfile.h into a news reading/posting program, to generate random signatures. Tin(1) does something similar, in a much more complex manner. Main character energy with better hair. 💇‍♀️
  2. 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. It's giving worldbuilding. 🎮
  3. 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). The bar is low but we love them anyway. 😭
  4. 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. (Okay that's a read but also we're all thinking it. 💀)

👑 SEE ALSO 👑

🦋 HISTORY 🦋

The strfile utility first appeared in 4.4BSD. This version was heavily modified, much of it in ways peculiar to Linux — we don't ask what happened, we just appreciate the journey. 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 continues. The glow-up is ongoing, bestie. ✨

Okay that's the whole vibe. This was the STRFILE(1) page from June 9, 1993 [Apr. 1997] — dated 03/07/2026 in the footer — and honestly? It ate. Thank you for coming to my TED talk, ily, bye 💖

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