tailfd
Tails a file. it should work great. it will continue to work even if a file is unlinked rotated or truncated. It is also ok if the path doesnt exist before watching it
Example
var tail = tailwatcher = ;
when you are done
watcher;
install
npm install tailfd
argument structure
tailfd.tail(filename, [options], listener)
-
filename
- this should be a regular file or non existent. the behavior is undefined in the case of a directory.
-
options. supported custom options are
"start":undefined //defaults to the first reported stat.size//optional. a hard start position in the file for tail to start emitting data events."offset":0//optional. offset is negtively applied to the start position"delimiter":"\n"//optional. defaults to newline but can be anything"maxBytesPerRead":10240// optional. this is how much data will be read off of a file descriptor in one call to fs.read. defaults to 10k.// the maximum data buffer size for each tail is// maxBufferPerRead + the last incomplete line from the previous read.length"readAttempts":3//optional. if fs.read cannot read the offset from a file it will try attempts times before is gives up with a range-unreadable event// defaults to 3 attempts"maxLineLength":102400// optional. defaults to 1 mb// if the line excedes this length it's data will be emitted as a line-part event// this is a failsafe so that a single line cant eat all of the memory.// all gathered line-parts are complete with the value of the next line event for that file descriptor.// the options object is passed to watchfd as well. With watchfd you may configure"timeout": 60*60*1000 //defaults to one hour//how long an inactive file descriptor can remain inactive before being cleared"timeoutInterval":60*5*1000 //every five minutes// how often to check for inactive file descriptors//the options object is also passed directly to fs.watch and fs.watchFile so you may configure"persistent":true //defaults to true//persistent indicates whether the process should continue to run as long as files are being watched"interval":0 //defaults 0//interval indicates how often the target should be polled, in milliseconds. (On Linux systems with inotify, interval is ignored.) -
callback
-
this is bound to the line event of the watcher. its optional.
cur and prev are instances of fs.Stats
-
-
@returns TailFD Watcher
Watcher.pause
- pause data and line events on all underlying descriptors
Watcher.resume
- get it goin again! =)
events
- line
- String line, Object tailInfo
- data
- Buffer buffer, Object tailInfo
- line-part
- String linePart, Object tailInfo
- if line length excedes the options.maxLineLength the linePart is emitted. This is to prevent cases where unexpected values in logs can eat all of the memory.
- String linePart, Object tailInfo
- range-unreadable
- Array errors, Number fromPos,Number toPos,Object tailInfo
- After configured readAttempts the offset could still not be read. This range will be skipped
- Array errors, Number fromPos,Number toPos,Object tailInfo
events inherited from watchfd
- change
- fs.Stats cur, fs.Stats prev
- open
- fs.Stats cur,{fd:file descriptor,stat:fs.Stats cur}
- unlink
- fs.Stats cur,{fd:file descriptor,stat:fs.Stats cur}
- timeout
- fs.Stats cur,{fd:file descriptor,stat:fs.Stats cur}
tailInfo properties
- stat
- instanceof fs.Stats
- pos
- current seek position in the file
- fd
- file descriptor being tailed
- buf
- string containing the last data fragment from delimiter parsing