fadvise

file cache behavior control utility

TLDR

Suggest a file will be needed soon (preload into cache)

$ fadvise -a willneed [path/to/file]

Suggest dropping a file from cache (default advice)

$ fadvise [path/to/file]

Apply advice to a specific byte range

$ fadvise -a sequential -o [offset] -l [length] [path/to/file]

Apply advice to an open file descriptor

$ fadvise -a dontneed -d [fd]

Display help

$ fadvise -h

SYNOPSIS

fadvise [options] filefadvise [options] -d file-descriptor

fadvise is a simple wrapper around the posix_fadvise(2) system call. It provides the kernel with a hint about how an application intends to access a file so that the kernel can optimize I/O behavior and page cache usage.Useful for preloading files before heavy read workloads, or for dropping pages after a one-shot sequential read.

PARAMETERS

-a, --advice advice

Caching advice. One of: normal, sequential, random, noreuse, willneed, dontneed. Defaults to dontneed.

-d, --fd fd

Apply advice to the given open file descriptor instead of a path.

-o, --offset offset

Byte offset to start from (default 0).

-l, --length length

Number of bytes to apply advice to (0 = entire file, default).

-h, --help

Display help.

-V, --version

Display version.

CAVEATS

Part of util-linux. Advice is a hint to the kernel, not a command. Actual behavior depends on system memory pressure.