Return to Answer

find / chmod optimization

Both find and chmod have to read

1. all directory entries
2. the inodes for all these entries

You probably get a performance improvement by first reading all the entries and then all the inodes (on a rotating disk) because then the disk head does not move between the directory and the inodes). As chmod is stupid (as one of the other answers explains) it should be calles through find only. But even then it may help to read all the inodes before the first gets written (assuming you have enough free RAM for the disk cache). I suggest this:

find . -printf "" # reading the file names only find . ! -perm 775 -printf "" # reading all the inodes (file names are cached) find . ! -perm 775 -exec chmod 775 + # writing to the cache without reading from disk 

The good solution: ACLs

The good solution may be completely different: If the files are created in this directory (and not moved from somewhere else) then ACLs can do the job on the fly. You just have to set the default ACLs on the parent directory.

Further improvement may be reached by filesystem optimizations. If it is ext3/ext4 then you may run e2fsck -D from time to time. Maybe it helps to put this directory onto a separate volume. You may try different filesystems or filesystem settings (e.g. different inode sizes).

find / chmod optimization

Both find and chmod have to read

1. all directory entries
2. the inodes for all these entries

You probably get a performance improvement by first reading all the entries and then all the inodes (on a rotating disk) because then the disk head does not move between the directory and the inodes). As chmod is stupid (as one of the other answers explains) it should be called through find only. But even then it may help to read all the inodes before the first gets written (assuming you have enough free RAM for the disk cache). I suggest this:

find . -printf "" # reading the file names only find . ! -perm 775 -printf "" # reading all the inodes (file names are cached) find . ! -perm 775 -exec chmod 775 + # writing to the cache without reading from disk 

The good solution: ACLs

The good solution may be completely different: If the files are created in this directory (and not moved from somewhere else) then ACLs can do the job on the fly. You just have to set the default ACLs on the parent directory.

Further improvement may be reached by filesystem optimizations. If it is ext3/ext4 then you may run e2fsck -D from time to time. Maybe it helps to put this directory onto a separate volume. You may try different filesystems or filesystem settings (e.g. different inode sizes).

find / chmod optimization

Both find and chmod have to read

1. all directory entries
2. the inodes for all these entries

You probably get a performance improvement by first reading all the entries and then all the inodes (on a rotating disk) because then the disk head does not move between the directory and the inodes). As chmod is not stupid it probably does not make a big difference whether you filter the files through find. But it may help to read all the inodes before the first gets written (assuming you have enough free RAM for the disk cache). I suggest this:

find . -printf "" # reading the file names only find . ! -perm 775 -printf "" # reading all the inodes (file names are cached) find . ! -perm 775 -exec chmod 775 + # writing to the cache without reading from disk 

The good solution: ACLs

The good solution may be completely different: If the files are created in this directory (and not moved from somewhere else) then ACLs can do the job on the fly. You just have to set the default ACLs on the parent directory.

Further improvement may be reached by filesystem optimizations. If it is ext3/ext4 then you may run e2fsck -D from time to time. Maybe it helps to put this directory onto a separate volume. You may try different filesystems or filesystem settings (e.g. different inode sizes).

find / chmod optimization

Both find and chmod have to read

1. all directory entries
2. the inodes for all these entries

You probably get a performance improvement by first reading all the entries and then all the inodes (on a rotating disk) because then the disk head does not move between the directory and the inodes). As chmod is stupid (as one of the other answers explains) it should be calles through find only. But even then it may help to read all the inodes before the first gets written (assuming you have enough free RAM for the disk cache). I suggest this:

find . -printf "" # reading the file names only find . ! -perm 775 -printf "" # reading all the inodes (file names are cached) find . ! -perm 775 -exec chmod 775 + # writing to the cache without reading from disk 

The good solution: ACLs

The good solution may be completely different: If the files are created in this directory (and not moved from somewhere else) then ACLs can do the job on the fly. You just have to set the default ACLs on the parent directory.

Further improvement may be reached by filesystem optimizations. If it is ext3/ext4 then you may run e2fsck -D from time to time. Maybe it helps to put this directory onto a separate volume. You may try different filesystems or filesystem settings (e.g. different inode sizes).

find / chmod optimization

Both find and chmod have to read

1. all directory entries
2. the inodes for all these entries

You probably get a performance improvement by first reading all the entries and then all the inodes (on a rotating disk) because then the disk head does not move between the directory and the inodes). As chmod is not stupid it probably does not make a big difference whether you filter the files through find. But it may help to read all the inodes before the first gets written (assuming you have enough free RAM for the disk cache). I suggest this:

find . -printf "" # reading the file names only find . ! -perm 775 -printf "" # reading all the inodes (file names are cached) find . ! -perm 775 -exec chmod 775 + # writing to the cache without reading from disk 

Too much data for the cache

If the number of files is too high for your disk cache then you may use this for limiting the number of files which are read and worked on at once:

find . -print0 | xargs -0 /bin/bash -c '/usr/bin/stat --printf= "$@"; /usr/bin/chmod 775 "$@"' wrapper 

The good solution: ACLs

The good solution may be completely different: If the files are created in this directory (and not moved from somewhere else) then ACLs can do the job on the fly. You just have to set the default ACLs on the parent directory.

Further improvement may be reached by filesystem optimizations. If it is ext3/ext4 then you may run e2fsck -D from time to time. Maybe it helps to put this directory onto a separate volume. You may try different filesystems or filesystem settings (e.g. different inode sizes).

find / chmod optimization

Both find and chmod have to read

1. all directory entries
2. the inodes for all these entries

You probably get a performance improvement by first reading all the entries and then all the inodes (on a rotating disk) because then the disk head does not move between the directory and the inodes). As chmod is not stupid it probably does not make a big difference whether you filter the files through find. But it may help to read all the inodes before the first gets written (assuming you have enough free RAM for the disk cache). I suggest this:

find . -printf "" # reading the file names only find . ! -perm 775 -printf "" # reading all the inodes (file names are cached) find . ! -perm 775 -exec chmod 775 + # writing to the cache without reading from disk 

The good solution: ACLs

The good solution may be completely different: If the files are created in this directory (and not moved from somewhere else) then ACLs can do the job on the fly. You just have to set the default ACLs on the parent directory.

Further improvement may be reached by filesystem optimizations. If it is ext3/ext4 then you may run e2fsck -D from time to time. Maybe it helps to put this directory onto a separate volume. You may try different filesystems or filesystem settings (e.g. different inode sizes).