mtail.py

   1 #!/usr/bin/env python
   2
   3 '''
   4 Does tail -f on log files in a given directory.
   5 The display is in chronological order of the logged lines,
   6 given that the first column of log files is timestamp.
   7 It can be altered to fit other formats too
   8 '''
   9
  10 import os, sys, time
  11 from optparse import OptionParser
  12
  13 class mtail:
  14
  15     subversion_id = "$Id$"
  16
  17     default_time_format = "%H:%M:%S"
  18
  19     def __init__ (self, args ):
  20
  21         # internal structure for tracking changes
  22         self.files = {}
  23         # parse command-line args : will set options and args
  24         self.parse_args(args)
  25         # initialize
  26         self.scan_files()
  27
  28     def parse_args (self, args):
  29         usage = """usage: %prog [options] file-or-dir ...
  30 example:
  31 # %prog -e '*access*' /var/log"""
  32         parser=OptionParser(usage=usage,version=self.subversion_id)
  33         # tail_period
  34         parser.add_option("-p","--period", type="int", dest="tail_period", default=1,
  35                           help="Files check period in seconds")
  36         # rescan_period
  37         parser.add_option("-d","--dir-period", type="int", dest="rescan_period", default=20,
  38                           help="Directories rescan period in seconds")
  39         # time format
  40         parser.add_option("-f","--format", dest="time_format", default=mtail.default_time_format,
  41                           help="Time format, defaults to " + mtail.default_time_format)
  42         # show time
  43         parser.add_option("-r","--raw", action="store_true", dest="show_time", default=True,
  44                           help="Suppresses time display")
  45
  46         # note for exclusion patterns
  47         parser.add_option("-e","--exclude", action="append", dest="excludes", default=[],
  48                           help="Exclusion pattern  -- can be specified multiple times applies on files not explicitly mentioned on the command-line")
  49
  50         parser.add_option("-u","--usual",action="store_true",dest="plc_mode",default=False,
  51                           help="Shortcut for watching /var/log with default settings")
  52
  53         # verbosity
  54         parser.add_option("-v","--verbose", action="store_true", dest="verbose", default=False,
  55                           help="Run in verbose mode")
  56
  57         (self.options, self.args) = parser.parse_args(args)
  58         self.optparse = parser
  59
  60         ### plc shortcuts
  61         if self.options.plc_mode:
  62             self.options.excludes.append('*access_log')
  63             self.options.excludes.append('*request_log')
  64             self.options.excludes.append('*.swp')
  65             self.args.append('/var/log')
  66
  67         if self.options.verbose:
  68             print 'Version:',self.subversion_id
  69             print 'Options:',self.options
  70             print 'Arguments:',self.args
  71
  72     def file_size (self,filename):
  73         return os.stat(filename)[6]
  74
  75     def number_files (self):
  76         return len(self.files)
  77
  78     # scans given arguments, and updates files accordingly
  79     # can be run several times
  80     def scan_files (self) :
  81
  82         if self.options.verbose:
  83             print 'entering scan_files, files=',self.files
  84
  85         # mark entries in files as pre-existing
  86         for key in self.files:
  87             self.files[key]['old-file']=True
  88
  89         # refreshes the proper set of filenames
  90         filenames = []
  91         for arg in self.args:
  92             if self.options.verbose:
  93                 print 'scan_files -- Considering arg',arg
  94             if os.path.isfile (arg):
  95                 filenames += [ arg ]
  96             elif os.path.isdir (arg) :
  97                 filenames += self.walk (arg)
  98             else:
  99                 print "mtail : no such file or directory %s -- ignored"%arg
 100
 101         # updates files
 102         for filename in filenames :
 103             # known file
 104             if self.files.has_key(filename):
 105                 size = self.file_size(filename)
 106                 offset = self.files[filename]['size']
 107                 if size > offset:
 108                     self.show_file_end(filename,offset,size)
 109                     self.files[filename]['size']=size
 110                 elif size < offset:
 111                     self.show_file_when_size_decreased(filename,offset,size)
 112                 del self.files[filename]['old-file']
 113             else:
 114                 # enter file with current size
 115                 # if we didn't set format yet, it's because we are initializing
 116                 try:
 117                     self.format
 118                     self.show_now()
 119                     print self.format%filename,"new file"
 120                     self.show_file_end(filename,0,self.file_size(filename))
 121                 except:
 122                     pass
 123                 self.files[filename]={'size':self.file_size(filename)}
 124
 125         # cleanup
 126         # avoid side-effects on the current loop basis
 127         read_filenames = self.files.keys()
 128         for filename in read_filenames:
 129             if self.files[filename].has_key('old-file'):
 130                 self.show_now()
 131                 print self.format%filename,"file has gone"
 132                 del self.files[filename]
 133
 134         # compute margin and format
 135         if not filenames:
 136             print sys.argv[0],": WARNING : no file in scope"
 137             self.format="%s"
 138         else:
 139             self.margin=max(*[len(f) for f in filenames])
 140             self.format="%%%ds"%self.margin
 141             if self.options.verbose:
 142                 print 'Current set of files:',filenames
 143
 144     def tail_files (self):
 145
 146         if self.options.verbose:
 147             print 'tail_files'
 148         for filename in self.files:
 149             size = self.file_size(filename)
 150             offset = self.files[filename]['size']
 151             if size != offset:
 152                 self.show_file_end(filename,offset,size)
 153                 self.files[filename]['size']=size
 154
 155     def show_now (self):
 156         if self.options.show_time:
 157             label=time.strftime(self.options.time_format,time.localtime())
 158             print label,
 159
 160     def show_file_end (self, filename, offset, size):
 161         file = open(filename,"r")
 162         file.seek(offset)
 163         line=file.read(size-offset)
 164         self.show_now()
 165         print self.format%filename,'----------------------------------------'
 166         print line
 167         file.close()
 168
 169     def show_file_when_size_decreased (self, filename, offset, size):
 170         print self.format%filename,'---------- file size decreased ---------',
 171         if self.options.verbose:
 172             print 'size during last check',offset,'current size',size
 173         else:
 174             print ''
 175
 176     # get all files under a directory
 177     def walk ( self, root ):
 178         import fnmatch, os, string
 179
 180         # initialize
 181         result = []
 182
 183         # must have at least root folder
 184         try:
 185             names = os.listdir(root)
 186         except os.error:
 187             return result
 188
 189         # check each file
 190         for name in names:
 191             fullname = os.path.normpath(os.path.join(root, name))
 192
 193             # a file : check for excluded, otherwise append
 194             if os.path.isfile(fullname):
 195                 try:
 196                     for exclude in self.options.excludes:
 197                         if fnmatch.fnmatch(name, exclude):
 198                             raise Exception('excluded')
 199                     result.append(fullname)
 200                 except:
 201                     pass
 202             # a dir : let's recurse - avoid symlinks for anti-loop
 203             elif os.path.isdir(fullname) and not os.path.islink(fullname):
 204                 result = result + self.walk( fullname )
 205
 206         return result
 207
 208     def run (self):
 209
 210         if self.number_files() == 0:
 211             self.optparse.print_help()
 212             sys.exit(1)
 213         counter = 0
 214
 215         while 1:
 216             ## hit the period ?
 217             # dont do this twice at startup
 218             if (counter !=0 and counter % self.options.rescan_period == 0):
 219                 self.scan_files()
 220
 221             if (counter % self.options.tail_period == 0):
 222                 self.tail_files()
 223
 224             time.sleep(1)
 225             counter += 1
 226
 227 ###
 228 if __name__ == '__main__':
 229     mtail (sys.argv[1:]).run()