s6-fdholder-transferdump.html (3389B)
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-transferdump program</title> 7 <meta name="Description" content="s6: the s6-fdholder-transferdump program" /> 8 <meta name="Keywords" content="s6 s6-fdholder fd-holding fd-holder fd dump transfer 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-transferdump</tt> program </h1> 20 21 <p> 22 <tt>s6-fdholder-transferdump</tt> connects to two separate 23 <a href="s6-fdholderd.html">fd-holding daemons</a> and 24 transfers the content of the first one to the second one. 25 </p> 26 27 <h2> Interface </h2> 28 29 <pre> 30 s6-fdholder-transferdump [ -t <em>timeoutfrom:timeoutto</em> ] <em>pathfrom</em> <em>pathto</em> 31 </pre> 32 33 <ul> 34 <li> <tt>s6-fdholder-transferdump</tt> connects to a 35 <a href="s6-fdholderd.html">s6-fdholderd</a> server process listening on 36 <em>pathfrom</em> and gets the whole set of file descriptors from 37 this server, with their identifiers and (when relevant) expiration 38 dates. </li> 39 <li> It then connects to a different instance of 40 <a href="s6-fdholderd.html">s6-fdholderd</a>, listening on <em>pathto</em>, 41 and stores the set of file descriptors to it. The set is 42 <em>added</em> to the second server, which keeps the descriptors 43 it was already holding. </li> 44 </ul> 45 46 <h2> Options </h2> 47 48 <ul> 49 <li> <tt>-t <em>timeoutfrom</em>:<em>timeoutto</em></tt> : 50 if the operations cannot be 51 processed in <em>timeoutfrom</em> (for the connection to <em>pathfrom</em>) 52 or <em>timeoutto</em> (for the connection to <em>pathto</em>) milliseconds, 53 then fail with an error message. 54 Communications with the servers 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 source server denied the operation. The meaning of the error messages 64 is explained <a href="s6-fdholder-errorcodes.html">here</a>. </li> 65 <li> 2: the destination server denied the operation. The meaning of the error messages 66 is explained <a href="s6-fdholder-errorcodes.html">here</a>. </li> 67 <li> 100: wrong usage. </li> 68 <li> 111: system call failed - this includes attempting to connect to a 69 nonexistent socket, or one where no <a href="s6-fdholderd.html">s6-fdholderd</a> 70 daemon is listening. </li> 71 </ul> 72 73 <h2> Notes </h2> 74 75 <ul> 76 <li> Dumping the entire state of <a href="s6-fdholderd.html">s6-fdholderd</a> 77 requires special authorizations. Make sure the s6-fdholderd instances are 78 <a href="s6-fdholderd.html#configuration">configured</a> to accept 79 dump-getting and dump-setting requests from your client. </li> 80 <li> A typical use case of 81 <a href="s6-fdholder-transferdump.html">s6-fdholder-transferdump</a> is 82 when the main fd-holding daemon needs to upgrade, or restart for some reason. 83 Transferring the file descriptors into another, temporary fd-holding daemon 84 instance allows it to restart without losing the descriptors. </li> 85 </ul> 86 87 </body> 88 </html>