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Full Discussion: Too many files to list / remove
Top Forums UNIX for Dummies Questions & Answers Too many files to list / remove Post 25662 by Perderabo on Friday 2nd of August 2002 08:06:46 AM
Old 08-02-2002
Handling a directory this large is going to require very careful attention to performance considerations. I usually hold my tongue when I see someone suggest the -exec option on a "find" command. But in this case, it will be a very large problem. A command like:

find /path/directory/ -mtime +29 -exec ls {} \;

is going to launch one "ls" process for each file. In this case, that is way too many. We need to get as many files on the "ls" (or "rm") command line as possible. That way, a single process will be handling dozens or maybe hundreds of files at once. We can do this with:

cd /path/directory
find . -mtime +29 -print | xargs ls -d

(I always use -d in a case like this in case the "find" output a subdirectory.) By cd'ing to the directory first and then use "." in the "find" command, we shorten the pathname that find will output. This means that xargs can collect more of them for each "ls" process that it invokes.

Using xargs is always better than -exec, but with a small number of files, it's not a big deal.

Peter may have meant "ls", the OP did request help obtaining such a listing. But can anyone read a listing that is 600,000 lines long? There is really no point to such a listing.

Any shell script written to process these files will also need careful attention to performance.
This:

for each_file in /path/directory/*

is not going to work. The shell will try to expand that asterisk and it will fail. Something like this:

#! /usr/bin/ksh
cd /path/directory
find . -print | while read each_file ; do

will work, but whatever the loop does it must be carefully coded. It must use only shell built-in commands and maybe some pre-launched co-processes. Invoking even 4 or 5 processes per loop will mean millions of total processes. Such a script would take a very long time to run.
 

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LEARN ABOUT ULTRIX

crontab

crontab(5)							File Formats Manual							crontab(5)

Name
       crontab - clock daemon table file

Syntax
       /usr/lib/crontab

Description
       The  command  executes  at  specified dates and times according to the instructions in the file. The file consists of lines with six fields
       each.  The format for a line is as follows:

	      minute hour day month weekday command

       The following list defines each field in the line:

       minute (0-59)  The exact minute that the command sequence executes.

       hour (0-23)    The hour of the day that the command sequence executes.

       day (1-31)     The day of the month that the command sequence executes.

       month (1-12)   The month of the year that the command sequence executes.

       weekday (1-7)  The day of the week that the command sequence executes. Monday = 1, Tuesday = 2, and so forth.

       command	      The complete command sequence variable that is to be executed.  Note that the command string must conform  to  Bourne  shell
		      syntax.

       The first five integer fields may be specified as follows:

       o   A single number in the specified range

       o   Two numbers separated by a minus, meaning a range inclusive

       o   A list of numbers separated by commas, meaning any of the numbers

       o   An asterisk meaning all legal values

       The sixth field is a string that is executed by the shell at the specified times.  A percent sign (%) in this field is translated to a new-
       line character.	Only the first line of the command field, up to a percent sign (%) or end of line, is executed by the  shell.	The  other
       lines are made available to the command as standard input.

Examples
       The following example is part of a file:
       # periodic things
       0,15,30,45 * * * * (echo '^M' `date`; echo '') >/dev/console
       0,15,30,45 * * * * /usr/lib/atrun

       # daily stuff
       5 4 * * * sh /usr/adm/newsyslog
       15 4 * * * ( cd /usr/preserve; find . -mtime +7 -a -exec rm -f {} ; )
       20 4 * * * find /usr/msgs -mtime +21 -a ! -perm 444 -a ! -name bounds
	    -a -exec rm -f {} ;

       # NOTE: The above line is wrapped.

       # local cleanups
       30 4 * * * find /usr/spool/mqueue -type f -mtime +5 -name df-exec rm {} ;
       35 4 * * * find /usr/spool/mqueue -type f -mtime +5 -name tf-exec rm {} ;
       40 4 * * * find /usr/spool/rwho -type f -mtime +21 -exec rm {} ;
       #

       # redirecting error output
       0 17 * * 1,3,5 /bin/tar -cv /usr/sysads/smith > /dev/console 2>&1
       #

Files
See Also
       sh(1), cron(8)
       Guide to System Environment Setup

																	crontab(5)
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