README.md

   1 # `fag` (Fork After Grep)
   2
   3 ```
   4 fag(1)                           User Commands                          fag(1)
   5
   6 NAME
   7        fag - daemonize program after a string was found (ForkAfterGrep)
   8
   9 SYNOPSIS
  10        fag [OPTIONS] PATTERN PROGRAM [ARGUMENTS...]
  11
  12 DESCRIPTION
  13        fag  uses  grep  to  search  the  output  of  PROGRAM  for  the regular
  14        expression PATTERN and daemonizes it when a match is found. The PID  is
  15        then returned on stdout.
  16
  17 OPTIONS
  18    Behaviour Changing Options
  19        -t SECONDS
  20               Set a timeout of SECONDS seconds.
  21
  22        -k [SIGNAL]
  23               If  given, send a signal to PROGRAM.  SIGNAL defaults to SIGTERM
  24               (15).  Right now, only decimal notation is implemented.
  25
  26        -e     Search PATTERN on stderr instead of stdout.
  27
  28        -V     Be verbose; print program's stdout (or stderr if -e is  set)  to
  29               stderr.
  30
  31    Generic Program Information
  32        -h     Output a short usage message and exit.
  33
  34        -v     Display version and copyright information and exit.
  35
  36 EXIT STATUS
  37        If PATTERN was found, 0 is returned. Otherwise, the exit status follows
  38        the BSD guideline  outlined  in  #include  <sysexits.h>  if  the  error
  39        occured  from within fag or in case the chid process exits prematurely,
  40        its exit code is inherited. Notably, 69 is returned when the timeout is
  41        reached.
  42
  43 BUGS
  44    Known Bugs
  45        if  grep  exits  with a code > 0, fag should terminate with grep's exit
  46        code and an error message. instead, fag exits as if a match was found.
  47
  48        Sometimes, stdin behaves strange after the program terminates.
  49
  50    Reporting Bugs
  51        Please  report   bugs   and   patches   to   the   issue   tracker   at
  52        https://github.com/girst/forkaftergrep/.
  53
  54 NOTES
  55        SIGNAL needs to be given as an integer. implementing mnemonics is dirty
  56        and not very portable; maybe support in the future.
  57
  58 COPYRIGHT
  59        Copyright  2017  Tobias  Girstmair.  This   is   free   software;   see
  60        https://www.gnu.org/licenses/gpl-3.0.html for conditions.
  61
  62 AUTHOR
  63        Tobias Girstmair (http://isticktoit.net)
  64
  65 1.0                             12 August 2017                          fag(1)
  66 ```
  67
  68 ## Notes
  69
  70 I've written this program for the [`tzap`/`szap`](https://linuxtv.org/wiki/index.php/Zap) utilities. They take a few seconds until the TV card/stick is tuned, and won't fork off when they are ready (If you terminate them, the tuning will end). Instead of waiting a few seconds, and hoping for the best, this does the exactly right thing.