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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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mktrashcan(1)						      General Commands Manual						     mktrashcan(1)

NAME
mktrashcan, rmtrashcan, shtrashcan - Attaches, detaches, or shows a trashcan directory SYNOPSIS
/usr/sbin/mktrashcan trashcan directory... /usr/sbin/rmtrashcan directory... /usr/sbin/shtrashcan directory... OPERANDS
Specifies the directory that contains files that were deleted from attached directories. Whenever you delete a file in the specified directory, the file system automatically moves the file to the trashcan directory. Specifies the directory that you attach to a trashcan directory. DESCRIPTION
The trashcan utilities (mktrashcan and rmtrashcan) enable you to attach or detach an existing directory, which you specify as a trashcan directory, to any number of directories within the same fileset. A trashcan directory stores the files that are deleted with the unlink system call. For instance, you can use the mktrashcan utility to attach a trashcan directory called /usr/trashcan to one or more directories; thereafter, when you delete a file from one of the attached directories, the file system moves the file to the /usr/trashcan directory. Note that when more than one directory shares attachment to a trashcan directory, files with the same file name can overwrite each other in the trashcan directory. If you mistakenly delete a file, use the mv command to return the file from the /usr/trashcan directory to its original directory. When you enter shtrashcan at the system prompt, the system shows the trashcan directory, if one exists, for the directory you specified. It is important that trashcan directories have correct access permissions. If the permissions are too restrictive, then it may be impossi- ble to remove files from the directories that are attached to the trashcan directory. In general, all users and groups that expect to use the trashcan directory need write permission to the directory. If unexpected "permission denied" errors occur when deleting files that are in a directory attached to a trashcan directory, use the chmod command to change the permissions on the trashcan directory. RESTRICTIONS
The directory and trashcan directories must be in the same fileset; however, you can attach the trashcan directory to any directory within the fileset. EXAMPLES
The following example creates and attaches a trashcan directory, /usr/trashcan, to two directories, /usr/ray and /usr/projects/sql/test, which are in the same fileset. The chmod command adds write permission for all users and groups on the new trashcan directory. % mkdir /usr/trashcan % chmod a+w /usr/trashcan % mktrashcan /usr/trashcan /usr/ray /usr/projects/sql/test To attach the trashcan directory, /usr/trashcan, to all subdirectories in the /usr directory, enter: % mktrashcan /usr/trashcan /usr/* New subdirectories that you add beneath the /usr directory are not attached to the trashcan directory until you attach them. Also, the mktrashcan utility distinguishes between directories and files, attaching only directories to the trashcan directory. Note that an attached directory produces an EDUPLICATE_DIRS (-1165) error when /usr/trashcan is itself in the directory path you attach to (as in the previous example). You can ignore this error message. SEE ALSO
advfs(4), mkfset(8), showfsets(8) mktrashcan(1)
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