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Top Forums Shell Programming and Scripting Increase the performance of find command. Post 303041939 by jim mcnamara on Saturday 7th of December 2019 09:28:02 AM
Old 12-07-2019
This standard library call: nftw (or ftw)
IBM Knowledge Center

supports the find command traversing directory file trees - i.e., searching and locating files.

Assuming you want to keep the command you already have (and I am not sue that Rudi's suggested test is valid because of file and directory caching ):

A limiting factor is known to be the number of sub-directories in the file tree, and possibly the number of available open file descriptors - a per process limit.
If you can parallelize your code using several processes it may improve performance. I'm not sure this will help much because it depends on the number of sub-directories being large to gain any benefit. The developers who write system code try to maximize throughput.

What I'm saying is: performance enhancement work is subjective and often a misplaced resource and a waste of programmer time.
Suppose your command runs in one minute in production. Then you work hard and get it down to 35 seconds. The user perception of "slow" will still be there, so you have to get it down to maybe 6 seconds to make users happy and see it as "faster". In this case getting an order of magnitude improvement may not be possible.

And in this case you would have to do something about directory caching messing up testing because (you check this yourself) once you open a directory the system caches it for speedier access. Use the time command and rerun the command to see what I mean:
Code:
time [my long command goes here]
#write down the result
time [my long command goes here]
# write down the result and compare the two resulting times

This User Gave Thanks to jim mcnamara For This Post:
 

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FIND(1) 						      General Commands Manual							   FIND(1)

NAME
find - find files SYNOPSIS
find pathname-list expression DESCRIPTION
Find recursively descends the directory hierarchy for each pathname in the pathname-list (i.e., one or more pathnames) seeking files that match a boolean expression written in the primaries given below. In the descriptions, the argument n is used as a decimal integer where +n means more than n, -n means less than n and n means exactly n. -name filename True if the filename argument matches the current file name. Normal Shell argument syntax may be used if escaped (watch out for `[', `?' and `*'). -perm onum True if the file permission flags exactly match the octal number onum (see chmod(1)). If onum is prefixed by a minus sign, more flag bits (017777, see stat(2)) become significant and the flags are compared: (flags&onum)==onum. -type c True if the type of the file is c, where c is b, c, d or f for block special file, character special file, directory or plain file. -links n True if the file has n links. -user uname True if the file belongs to the user uname (login name or numeric user ID). -group gname True if the file belongs to group gname (group name or numeric group ID). -size n True if the file is n blocks long (512 bytes per block). -inum n True if the file has inode number n. -atime n True if the file has been accessed in n days. -mtime n True if the file has been modified in n days. -exec command True if the executed command returns a zero value as exit status. The end of the command must be punctuated by an escaped semi- colon. A command argument `{}' is replaced by the current pathname. -ok command Like -exec except that the generated command is written on the standard output, then the standard input is read and the command executed only upon response y. -print Always true; causes the current pathname to be printed. -newer file True if the current file has been modified more recently than the argument file. The primaries may be combined using the following operators (in order of decreasing precedence): 1) A parenthesized group of primaries and operators (parentheses are special to the Shell and must be escaped). 2) The negation of a primary (`!' is the unary not operator). 3) Concatenation of primaries (the and operation is implied by the juxtaposition of two primaries). 4) Alternation of primaries (`-o' is the or operator). EXAMPLE
To remove all files named `a.out' or `*.o' that have not been accessed for a week: find / ( -name a.out -o -name '*.o' ) -atime +7 -exec rm {} ; FILES
/etc/passwd /etc/group SEE ALSO
sh(1), test(1), filsys(5) BUGS
The syntax is painful. FIND(1)
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