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Full Discussion: Bash - proper way to append variable to stderr
Top Forums Shell Programming and Scripting Bash - proper way to append variable to stderr Post 303003639 by bakunin on Monday 18th of September 2017 12:55:20 PM
Old 09-18-2017
Quote:
Originally Posted by alex2005
In order to get the missing files logs i run:
Code:
for i in {1..8} ; do ls -al file$i 2>> error.log ; done

I am not sure what exactly you want to do, but in this case you can simply test for the existence of the file(s) and then construct your own error message:

Code:
for i in 1 2 3 4 5 6 7 8 ; do
     if [ ! -e "/path/to/file$i" ] ; then
          echo "File file$i is missing, date is: $(date)" >>/your/log/file
     fi
done

If you do this in ksh you have an even better and cleanlier way to do this:

Code:
#! /bin/ksh

exec 3>>/path/to/your/logfile        # open logfile for appending and use IOD 3 to address it.

print -u3 - "----- start of execution ( $(date) ) -----" # -u3 : send it to IOD 3
for i in 1 2 3 4 5 6 7 8 ; do
     if [ ! -e "/path/to/file$i" ] ; then
          print -u3 - "File file$i is missing, date is: $(date)"
     fi
done
print -u3 - "----- end of execution ( $(date) ) -----"

exec 3>&-     # close IO descriptor 3 again

This way you can open (and close) the file once and do not have to address it anew for every message you want to append. You also don't have to worry about one misplaced ">" instead of a ">>" wiping out the whole logfile. And you can use several such files at once by using IOD 4, 5, 6, ... too.

I hope this helps.

bakunin
This User Gave Thanks to bakunin For This Post:
alex2005
 

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LEARN ABOUT CENTOS

rotatelogs

ROTATELOGS(8)							    rotatelogs							     ROTATELOGS(8)

NAME

       rotatelogs - Piped logging program to rotate Apache logs

SYNOPSIS

       rotatelogs  [ -l ] [ -L linkname ] [ -p program ] [ -f ] [ -v ] [ -e ] [ -c ] [ -n number-of-files ] logfile rotationtime|filesize(B|K|M|G)
       [ offset ]

SUMMARY

       rotatelogs is a simple program for use in conjunction with Apache's piped logfile feature. It supports rotation based on a time interval or
       maximum size of the log.

OPTIONS

       -l     Causes the use of local time rather than GMT as the base for the interval or for strftime(3) formatting with size-based rotation.

       -L linkname
	      Causes  a  hard  link to be made from the current logfile to the specified link name. This can be used to watch the log continuously
	      across rotations using a command like tail -F linkname.

       -p program
	      If given, rotatelogs will execute the specified program every time a new log file is opened. The filename of the newly  opened  file
	      is  passed  as  the first argument to the program. If executing after a rotation, the old log file is passed as the second argument.
	      rotatelogs does not wait for the specified program to terminate before continuing to operate,  and  will	not  log  any  error  code
	      returned	on  termination.  The  spawned program uses the same stdin, stdout, and stderr as rotatelogs itself, and also inherits the
	      environment.

       -f     Causes the logfile to be opened immediately, as soon as rotatelogs starts, instead of waiting for the first logfile entry to be read
	      (for  non-busy  sites,  there  may  be a substantial delay between when the server is started and when the first request is handled,
	      meaning that the associated logfile does not "exist" until then, which causes problems from some automated logging tools)

       -t     Causes the logfile to be truncated instead of rotated. This is useful when a log is processed in real time by a command  like  tail,
	      and  there  is  no need for archived data. No suffix will be added to the filename, however format strings containing '%' characters
	      will be respected.

       -v     Produce verbose output on STDERR. The output contains the result of the configuration parsing, and all file open and close actions.

       -e     Echo logs through to stdout. Useful when logs need to be further processed in real time by a further tool in the chain.

       -c     Create log file for each interval, even if empty.

       -n number-of-files
	      Use a circular list of filenames without timestamps. With -n 3, the series of log files  opened  would  be  "logfile",  "logfile.1",
	      "logfile.2", then overwriting "logfile".

       logfile

       rotationtime
	      The  time between log file rotations in seconds. The rotation occurs at the beginning of this interval. For example, if the rotation
	      time is 3600, the log file will be rotated at the beginning of every hour; if the rotation time is  86400,  the  log  file  will	be
	      rotated every night at midnight. (If no data is logged during an interval, no file will be created.)

       filesize(B|K|M|G)
	      The  maximum  file size in followed by exactly one of the letters B (Bytes), K (KBytes), M (MBytes) or G (GBytes). .PP When time and
	      size are specified, the size must be given after the time. Rotation will occur whenever either time or size limits are reached.

       offset The number of minutes offset from UTC. If omitted, zero is assumed and UTC is used. For example, to use local time in the  zone  UTC
	      -5 hours, specify a value of -300 for this argument. In most cases, -l should be used instead of specifying an offset.

EXAMPLES

	    CustomLog "|bin/rotatelogs /var/logs/logfile 86400" common

       This  creates  the files /var/logs/logfile.nnnn where nnnn is the system time at which the log nominally starts (this time will always be a
       multiple of the rotation time, so you can synchronize cron scripts with it). At the end of each rotation time (here after 24 hours)  a  new
       log is started.

	    CustomLog "|bin/rotatelogs -l /var/logs/logfile.%Y.%m.%d 86400" common

       This  creates  the files /var/logs/logfile.yyyy.mm.dd where yyyy is the year, mm is the month, and dd is the day of the month. Logging will
       switch to a new file every day at midnight, local time.

	    CustomLog "|bin/rotatelogs /var/logs/logfile 5M" common

       This configuration will rotate the logfile whenever it reaches a size of 5 megabytes.

	    ErrorLog "|bin/rotatelogs /var/logs/errorlog.%Y-%m-%d-%H_%M_%S 5M"

       This configuration will rotate the error logfile whenever it reaches a size of 5 megabytes, and the suffix to the logfile name will be cre-
       ated of the form errorlog.YYYY-mm-dd-HH_MM_SS.

	    CustomLog "|bin/rotatelogs -t /var/logs/logfile 86400" common

       This  creates  the file /var/logs/logfile, truncating the file at startup and then truncating the file once per day. It is expected in this
       scenario that a separate process (such as tail) would process the file in real time.

PORTABILITY

       The following logfile format string substitutions should be supported by all strftime(3) implementations, see the strftime(3) man page  for
       library-specific extensions.

       o %A - full weekday name (localized)

       o %a - 3-character weekday name (localized)

       o %B - full month name (localized)

       o %b - 3-character month name (localized)

       o %c - date and time (localized)

       o %d - 2-digit day of month

       o %H - 2-digit hour (24 hour clock)

       o %I - 2-digit hour (12 hour clock)

       o %j - 3-digit day of year

       o %M - 2-digit minute

       o %m - 2-digit month

       o %p - am/pm of 12 hour clock (localized)

       o %S - 2-digit second

       o %U - 2-digit week of year (Sunday first day of week)

       o %W - 2-digit week of year (Monday first day of week)

       o %w - 1-digit weekday (Sunday first day of week)

       o %X - time (localized)

       o %x - date (localized)

       o %Y - 4-digit year

       o %y - 2-digit year

       o %Z - time zone name

       o %% - literal `%'

Apache HTTP Server						    2013-06-13							     ROTATELOGS(8)
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