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Commands tagged I/O from sorted by
Terminal - Commands tagged I/O - 4 results
find /path/to/dir -type f -exec cachedel '{}' \;
2013-12-12 18:22:54
User: michelsberg
Functions: find
-1

This is just another example of what the nocache package is useful for, which I described in http://www.commandlinefu.com/commands/view/12357/ and that provides the commands

nocache <command to run with page cache disabled>

cachedel <single file to remove from page cache>

cachstats <single file> # to get the current cache state

Often, we do not want to disable caching, because several file reads are involved in a command and operations would be slowed down a lot, due to massive disk seeks. But after our operations, the file sits in the cache needlessly, if we know we're very likely never touching it again.

cachedel helps to reduce cache pollution, i.e. frequently required files relevant for desktop interaction (libs/configs/etc.) would be removed from RAM.

So we can run cachedel after each data intensive job. Today I run commands like these:

<compile job> && find . -type f -exec cachedel '{}' \; &> /dev/null # no need to keep all source code and tmp files in memory

sudo apt-get dist-upgrade && find /var/cache/apt/archives/ -type f -exec cachedel '{}' \; # Debian/*buntu system upgrade

dropbox status | grep -Fi idle && find ~/Dropbox -type f -exec cachedel '{}' \; &> /dev/null # if Dropbox is idle, remove sync'ed files from cache

https://github.com/Feh/nocache

http://packages.debian.org/search?keywords=nocache

http://packages.ubuntu.com/search?keywords=nocache

http://askubuntu.com/questions/122857

dd if=file | tee >(sha1sum) >(md5sum) >(sha256sum) >/dev/null
2013-11-07 17:43:54
User: dubbaluga
Functions: dd tee
Tags: tee parallel I/O
0

This is to overcome the issue of slow I/O by reading once and forwarding the output to several processes (e. g. 3 in the given command). One could also invoke grep or other programs to work on read data.

$text = do {local(@ARGV, $/) = $file ; <>; }; [or] sub read_file { local(@ARGV, $/) = @_ ; <>; }
2013-06-12 11:41:49
User: matya
0

Found it on:

http://stackoverflow.com/questions/318789/whats-the-best-way-to-open-and-read-a-file-in-perl

The yet most simple way to read all the contents of a file to a variable. I used it in a perl script to replace $text="`cat /sys/...`", and stipping down 9 secs of runtime due less forks

nocache <I/O-heavy-command>
2013-05-21 15:15:05
User: michelsberg
21

We all know...

nice -n19

for low CPU priority.

ionice -c3

for low I/O priority.

nocache can be useful in related scenarios, when we operate on very large files just a single time, e.g. a backup job. It advises the kernel that no caching is required for the involved files, so our current file cache is not erased, potentially decreasing performance on other, more typical file I/O, e.g. on a desktop.

http://askubuntu.com/questions/122857

https://github.com/Feh/nocache

http://packages.debian.org/search?keywords=nocache

http://packages.ubuntu.com/search?keywords=nocache

To undo caching of a single file in hindsight, you can do

cachedel <OneSingleFile>

To check the cache status of a file, do

cachestats <OneSingleFile>