Questions tagged [buffer]

This tag is for questions about kernel buffer caches, including pipe buffers. These are used to store the recently accessed files and/or frequently accessed files.

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3
votes
1answer
269 views

Artificially prime buffer cache?

Is it beneficial to artificially prime the buffer cache when dealing with larger files? Here's a scenario: A large file needs to be processed, line by line. Conceptually, it is easy to parallelize ...
8
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3answers
2k views

Piping commands, modify stdin write to stdout

echo Hello World | nano - | less I want to modify Hello -> Goodbye while in the the text editor. It does not have to be with nano. I am stuck with nano reading stdin but requiring me to write to a ...
5
votes
2answers
2k views

How to control buffering of pipes in bash scripts?

I need my script to be executed with stdbuf -i0 -o0 -e0 otherwise user will wonder why there is no output (becuase of pipe buffer). How can I acheive it? #!/usr/bin/stdbuf -i0 -o0 -e0 /bin/bash ...
0
votes
1answer
536 views

Preventing a new instance of a program to open when calling it

My problem is with FBI (frame buffer image viewer) for Linux, but my question and any answers are perhaps applicable to more than only that program. I don't know. Anyway… While things are loading on ...
5
votes
1answer
2k views

Difference between “blockdev --flushbufs” and “sync” on Linux?

Is there a difference in practice between running blockdev --flushbufs and sync(1) on Linux? (apart from blockdev flushing for a specific device, and sync being system-wide). sync(1) manpage says it ...
13
votes
1answer
5k views

`unbuffer` or `stdbuf` for removing stdout buffering?

Is there a difference between unbuffer(1) and stdbuf(1)? From what I gather, unbuffer makes more than the "best effort" of calling the libc function set(X)buf at the beginning, and then letting things ...
4
votes
2answers
31k views

How to reduce buffers\cache

A monitoring system keeps alerting that my machine is reaching\breaking through it's RAM utilization threshold which is 15 GBs. I've done some reading and understood that the apparent RAM utilization ...
2
votes
1answer
381 views

Why don't I see a file being copied right away with ls?

Is it due to the buffering in memory? I did cp /network/large_file . & and I kept doing ls -lh to monitor progress, but the file didn't appear until it was about 400MB. Linux 2.6 kernel, Bash 4, ...
82
votes
12answers
38k views

vim - how can i do a 'change word' using the current paste buffer

I have some text in my paste buffer, e.g. I did a yw (yank word) and now I have 'foo' in my buffer. I now go to the word 'bar' and I want to replace it with my paste buffer. To replace the text ...
6
votes
3answers
3k views

Are there any ways or tools to dump the memory cache and buffer?

I want to check out what files are loaded in buffer. Just so it's clear, the buffers & cache I'm referring to are what show up when you run the free -m command: $ free -m total ...
1
vote
1answer
5k views

very high buffer memory usage [closed]

Is this normal - I've never seen buffers so high? $ cat /proc/meminfo MemTotal: 16332808 kB MemFree: 1112264 kB Buffers: 10630124 kB Cached: 699400 kB SwapCached: 0 kB Active: 3262924 kB Inactive: ...
2
votes
1answer
2k views

Daemontools multilog loses log line time information. How to fix it?

I am using daemontools to monitor a process and its output log. I am using multilog to write the logs to disk. The run script for the log is: #!/bin/bash PATH=/usr/local/bin:/usr/bin:/bin cd /usr/...
4
votes
3answers
1k views

Does sysctl kern.bufcachepercent not work in OpenBSD 5.2 above 1.7GB?

I run OpenBSD/amd64 5.2 on a system with 12GB of RAM, and I want to use about 6GB to 8GB for filesystem caching. By default, 5.2 amd64 comes with sysctl kern.bufcachepercent set to 20 (20%); I've ...
6
votes
1answer
1k views

Ksh loses data after piping 16K bytes

I recently found that ksh may lose some data after printing more than 16K bytes to the stdout if it is blocked for a couple of seconds. This test.sh script prints out 257*64 (16448) bytes: #!/usr/...
3
votes
0answers
138 views

xdelta3 fails to decode on block device

I'm trying to use xdelta3 to bring a remote block device into sync with a local one. I'm able to easily generate a xdelta3 patch file using the command: xdelta3 -e -B 33554432 -v -9 -I 0 -s /dev/...
6
votes
1answer
3k views

Switching between split buffers in vim

recently starting trying to use VIM as my full-time text editor since I spent a lot of time SSH'ed anyways. Recently installed NERDTree so I can quickly swap between files in a project. Easy question ...
6
votes
2answers
3k views

linux stdbuf - line-buffered stdin option does not exist

The man page for the stdbuf command states that line-buffered mode is invalid as a standard input buffering option. What is the reason for this? tail -f access.log | stdbuf -iL cut -d' ' -f1 | uniq ...
5
votes
2answers
9k views

Alternate FIFO device for Linux with a (way) bigger buffer while still having filesystem semantics?

I am developing something that consists of a program I made generating output, and a program I did not make (and would very much like not to have to alter it) consuming it. I am using a named FIFO ...
14
votes
2answers
3k views

“tail -f | iconv -fsjis” does not output anything

I want to tail -f a file, but its content is in sjis encoding, so I need to have it converted to the native (utf-8) encoding of my terminal. When I do tail -f x | iconv -fsjis there will be no ...
17
votes
5answers
5k views

Is there a way to sync only one partition?

Is there a way to sync only one partition instead of all partitions? Something like "sync /dev/sdc1".
1
vote
5answers
2k views

Display output to console while grep is used

In vim I use the following command to compile a tex file: pdflatex\ \-file\-line\-error\ \-shell\-escape\ \-interaction=nonstopmode\ $*\\\|\ grep\ \-P\ ':\\d{1,5}:\ ' this works in terms of getting ...
12
votes
5answers
3k views

Utility to buffer an unbounded amount of data in a pipeline?

Is there a utility that I can stick in a pipeline to decouple read and write speeds? $ producer | buf | consumer Basically, I want a utility buf that reads its input as fast as possible, storing it ...
18
votes
3answers
6k views

Prevent unwanted buffers from opening

I'm using emacs for my daily javascript editing, to switch between buffers I use C-x LEFT and C-x RIGHT and I'm fine with this (even if I find it difficult to know the path of the file I'm modifying). ...
16
votes
1answer
19k views

Buffer size for capturing packets in kernel space?

Going through the man page of tcpdump, it seems kernel can drop the packets if the buffer is full. I was wondering if: that size is configurable and/or where can I see the size for my distro? From ...
144
votes
6answers
139k views

How big is the pipe buffer?

As a comment in I'm confused as to why "| true" in a makefile has the same effect as "|| true" user cjm wrote: Another reason to avoid | true is that if the command produced ...
26
votes
3answers
5k views

Is there truth to the philosophy that you should sync; sync; sync; sync?

When I was first introduced to Linux, working at Cisco Systems in 2000, I was taught the merits of the sync command, used to flush buffers to disk to prevent filesystem corruption / data loss. I was ...
3
votes
1answer
354 views

Ex and Vi: buffers and regexes

I want to put regex matches to buffer but cannot get even simpler example y :.put myNewBuffer return msg [line] [put] [buffer] working ie how to put something to buffer? So to regular expressions ...
26
votes
3answers
9k views

How to change the name of a vim buffer

Is it possible to change the name of a buffer in vim? Specifically, I'm using Conque Shell to open shells in vim (each shell is in a buffer) and with multiple shells, I see: 10: bash - 1 11: bash - ...
394
votes
13answers
200k views

Turn off buffering in pipe

I have a script which calls two commands: long_running_command | print_progress The long_running_command prints a progress but I'm unhappy with it. I'm using print_progress to make it more nice (...