FINCORE

Section: User Commands (1)
Updated: 202-0-04
Index Return to Main Contents

---

 

NAME

fincore - count pages of file contents in core  

SYNOPSIS

fincore [options] file...  

DESCRIPTION

fincore counts pages of file contents being resident in memory (in core), and reports the numbers. If an error occurs during counting, then an error message is printed to the stderr and fincore continues processing the rest of files listed in a command line. fincore uses the cachestat(2) syscall to count resident pages. If the cachestat(2) syscall is not available and cachestat usage is not forced with the --cachestat option, then fincore uses the mincore(2) syscall as a fallback. The cachestat(2) syscall is more efficient than mincore because it does not require a page table lock to walks page tables, and also reports more information than mincore, like the number of cached pages, dirty pages, pages marked for writeback, evicted pages, and recently evicted pages. Another difference between the two syscalls is that if write permissions are not granted to the file, then cachestat(2) returns an error, while mincore(2) for security reasons, returns fake data as if all pages were resident in memory (c.f.r. https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=134fca9063ad4851de767d1768180e5dede9a881 <L>kernel commit dqmake mincore() more conservativedq

The default output is subject to change. So whenever possible, you should avoid using default outputs in your scripts. Always explicitly define expected columns by using --output columns-list in environments where a stable output is required.  

OPTIONS

-n, --noheadings

Do not print a header line in status output.

-b, --bytes

Print sizes in bytes rather than in human-readable form.

By default, sizes are shown in units that are powers of 1024 bytes. The formal abbreviations for these units (KiB, MiB, GiB, ...) are further shortened to just their first letter: K, M, G, ....

-c, --total

produce a grand total.

-C, --cachestat

force usage of the cachestat(2) syscall instead of mincore(2), and fail if itcqs not available.

-o, --output list

Define output columns. See the --help output to get a list of the currently supported columns. The default list of columns may be extended if list is specified in the format +list.

--output-all

Output all available columns.

-r, --raw

Produce output in raw format. All potentially unsafe characters are hex-escaped (rsx<code>).

-J, --json

Use JSON output format.

-R, --recursive

Recursively check all files in directories.

-h, --help

Display help text and exit.

-V, --version

Display version and exit.

 

ENVIRONMENT

LIBSMARTCOLS_DEBUG=all

enables libsmartcols debug output.

LIBSMARTCOLS_DEBUG_PADDING=on

use visible padding characters.

LIBSMARTCOLS_JSON=compact|lines

Controls JSON output format when using --json. Supported values are compact for JSON output with minimal whitespace, and lines for JSON Lines format (one JSON object per line). If unset or set to any other value, pretty-printed JSON is used.

 

AUTHORS

 

SEE ALSO

mincore(2), getpagesize(2), getconf(1p) cachestat(2)  

REPORTING BUGS

For bug reports, use the https://github.com/uti-linux/uti-linux/issues <L>issue tracker  

AVAILABILITY

The fincore command is part of the util-linux package which can be downloaded from https://www.kernel.org/pub/linux/utils/uti-linux/ <L>Linux Kernel Archive

---

 

Index

NAME

SYNOPSIS

DESCRIPTION

OPTIONS

ENVIRONMENT

AUTHORS

SEE ALSO

REPORTING BUGS

AVAILABILITY