[LU-17219] lfs find: add ability to print extended attributes

• Status: Open
• Project: Lustre
• Type: Improvement
• Priority: Minor
• Reporter: Thomas Bertschinger
• Assignee: WC Triage
• Resolution: Unresolved
• Severity: 3

Description

"lfs find" should have a printf option to be able to print extended attributes of files.

 

There are some design questions about the correct way for this to work:

• which xattrs should actually get printed? Should it only print xattrs that are matched with a supplied "-xattr" argument? what if no xattr argument is supplied?
• if multiple xattrs are printed per file should they be newline separated, or separated with some other character?
• different formats for printing, e.g., text, hex, base64, etc?

 

One of the main use cases for this would be printing job IDs for files that are matched with something like:
lfs find -xattr "user.job=" /mnt/lustre

Issue Links

• is related to: LU-15837 "lfs find -printf" improvements
• is related to: LU-15743 "lfs find" is missing "-xattr" support
• is related to: LU-13031 store JobID of program that created f...

Comments

[Andreas Dilger]

I'm thinking that the printing option should only print specific xattrs that are requested, though it would be possible to print all of the xattrs with a "*" wildcard. One option is the xattr specified by "--xattr", but that restricts the printing to specific xattrs that match a search criterion. That might be OK because why would we want to print an xattr that is not set on a file?

That said, my preference would be to have an option like "--printf %Lx:XATTR" to print XATTR as ASCII, and "--printf %LX:XATTR" to print XATTR as hex. It isn't totally clear if we want to also print the xattr name, but that could be part of the explicit printf format, like "--printf user.job=%Lx:XATTR" or similar. Alternately, there could be sub-options like "%Lxa:XATTR" to print the value in ASCII format, "%Lxh:XATTR" to print the value in hex, and "%Lxb" to print in base64. I don't think it makes sense to have a "%Lxn:XATTR" to print the xattr name, since that would just be XATTR, unless it is a glob pattern and we want to print the matching xattr names?