s6-fdholder-store.html (3822B)
1 <html> 2 <head> 3 <meta name="viewport" content="width=device-width, initial-scale=1.0" /> 4 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 5 <meta http-equiv="Content-Language" content="en" /> 6 <title>s6: the s6-fdholder-store program</title> 7 <meta name="Description" content="s6: the s6-fdholder-store program" /> 8 <meta name="Keywords" content="s6 s6-fdholder fd-holding fd-holder fd storage unix socket activation" /> 9 <!-- <link rel="stylesheet" type="text/css" href="//skarnet.org/default.css" /> --> 10 </head> 11 <body> 12 13 <p> 14 <a href="index.html">s6</a><br /> 15 <a href="//skarnet.org/software/">Software</a><br /> 16 <a href="//skarnet.org/">skarnet.org</a> 17 </p> 18 19 <h1> The <tt>s6-fdholder-store</tt> program </h1> 20 21 <p> 22 <tt>s6-fdholder-store</tt> connects to a 23 <a href="s6-fdholderd.html">fd-holding daemon</a> listening on a 24 Unix domain socket, and gives it a copy of one of its open file 25 descriptors for the daemon to hold. 26 </p> 27 28 <h2> Interface </h2> 29 30 <pre> 31 s6-fdholder-store [ -d <em>fd</em> ] [ -T fdtimeout ] [ -t <em>timeout</em> ] <em>path</em> <em>id</em> 32 </pre> 33 34 <ul> 35 <li> <tt>s6-fdholder-store</tt> connects to a 36 <a href="s6-fdholderd.html">s6-fdholderd</a> server process listening on 37 <em>path</em>. </li> 38 <li> It attempts to pass a copy of its standard input, or of its descriptor 39 <em>fd</em>, to the server, with identifier <em>id</em>. </li> 40 </ul> 41 42 <h2> Options </h2> 43 44 <ul> 45 <li> <tt>-d <em>fd</em></tt> : store descriptor number <em>fd</em>. 46 By default, <em>fd</em> is 0 (i.e. the program's stdin will be stored). </li> 47 <li> <tt>-T <em>fdtimeout</em></tt> : the descriptor is stored with 48 an expiration time of <em>fdtimeout</em> milliseconds, which means the 49 <a href="s6-fdholderd.html">s6-fdholderd</a> daemon will close and get rid of 50 the descriptor after this time. By default, <em>fdtimeout</em> is 0, which 51 means infinite - no expiration time. </li> 52 <li> <tt>-t <em>timeout</em></tt> : if the operation cannot be 53 processed in <em>timeout</em> milliseconds, then fail with an error message. 54 Communications with the server should be near-instant, so this option is 55 only here to protect users against programming errors (connecting to the 56 wrong socket, for instance). </li> 57 </ul> 58 59 <h2> Exit codes </h2> 60 61 <ul> 62 <li> 0: success. </li> 63 <li> 1: the server denied the operation. The meaning of the error messages 64 is explained <a href="s6-fdholder-errorcodes.html">here</a>. </li> 65 <li> 100: wrong usage. </li> 66 <li> 111: system call failed - this includes attempting to connect to a 67 nonexistent socket, or one where no <a href="s6-fdholderd.html">s6-fdholderd</a> 68 daemon is listening. </li> 69 </ul> 70 71 <h2> Usage example </h2> 72 73 <pre> 74 <a href="s6-ipcserver-socketbinder.html">s6-ipcserver-socketbinder</a> /tmp/mysocket s6-fdholder-store /service/fdholderd/s MYSOCKET 75 </pre> 76 77 <p> 78 will open a Unix domain socket, bind it to <tt>/tmp/mysocket</tt> and 79 listen to incoming connections, then give it to a 80 <a href="s6-fdholderd.html">s6-fdholderd</a> instance listening on 81 <tt>/service/fdholderd/s</tt>, with no expiration date, with the 82 "MYSOCKET" identifier. Another program will be able to retrieve the 83 socket later, using <a href="s6-fdholder-retrieve.html">s6-fdholder-retrieve</a>. 84 </p> 85 86 </body> 87 </html>