Sponsored Content
Top Forums UNIX for Dummies Questions & Answers Want to remove all lines but not latest 50 lines from a file Post 302868247 by drl on Saturday 26th of October 2013 05:34:08 PM
Old 10-26-2013
Hi.

Both of the solutions, shell variable and "dd move" are about the same as far as system resources go. I used alister's amended solution; his first failed (the one that went out with an email notification).

For a file of 14,754,910 lines, about 1 GB, the times for the shell solution keeping the last 50,000 lines were:
Code:
real	0m36.738s
user	0m1.624s
sys	0m8.321s

and for the clever "dd move" solution:
Code:
real	0m44.048s
user	0m1.408s
sys	0m8.725s

There were 2 wc executions for verification in both runs. Leaving those out:
Code:
real	0m29.443s
user	0m0.560s
sys	0m7.012s

and
Code:
real	0m30.536s
user	0m0.220s
sys	0m6.460s

The results actually surprised me -- I thought the shell would be slower. I saw paging being used a few times, slightly more often with the dd. The shell was run first, so cache advantage, if any, went to dd ... cheers, drl

This system:
Code:
 OS: Debian 5.0.8 lenny
 Kernel: x86_64 Linux 2.6.26-2-amd64
 Uptime: 59d 21h 58m
 CPU: AMD Athlon 64 3000+ @ 1.802GHz
 GPU: NVidia GeForce FX 5200
 RAM: 1170MB / 3024MB


Last edited by drl; 10-26-2013 at 06:39 PM.. Reason: Typo.
This User Gave Thanks to drl For This Post:
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

remove lines from file

file: 1 xxxxxxx 2 xxx xxx 5 xxx xxx ... 180 xxxxxx 200 xxx how to remove any lines with the first number range 1-180 (9 Replies)
Discussion started by: bluemoon1
9 Replies

2. Shell Programming and Scripting

To remove the lines in my file

Hi, There seems to some hack attempts in my site. I have attached the index page of my site and I need to remove the below lines from the index page. The below lines are at the center of the file. --> </style> <script>E V A L( unescape(... (5 Replies)
Discussion started by: gsiva
5 Replies

3. UNIX for Dummies Questions & Answers

vi to remove lines in file

All, I have a text file with several entries like below: personname personname.domain.com I know there is a way to use vi to remove only the personname.domain.com line. Can someone help? I believe that it involves /s/g/ something...I just can't remember the exact syntax. Thanks (2 Replies)
Discussion started by: kjbaumann
2 Replies

4. Shell Programming and Scripting

remove lines from file

Hi gurus, i'm trying to remove a number of lines from a large file using the following command: sed '1,5000d' oldfile > newfile Somehow the lines in the old file are not deleted... Am I doing this wrongly? Any suggestions? :confused: Thanks! :) wee (10 Replies)
Discussion started by: lweegp
10 Replies

5. Shell Programming and Scripting

remove : lines from file

A small question I have a test.txt file I have contents as: a:google b:yahoo : c:facebook : d:hotmail How do I remove the line with : my output should be a:google b:yahoo c:facebook d:hotmail (5 Replies)
Discussion started by: aronmelon
5 Replies

6. Shell Programming and Scripting

remove blank lines and merge lines in shell

Hi, I'm not a expert in shell programming, so i've come here to take help from u gurus. I'm trying to tailor a csv file that i got to make it work for the LOAD FROM command. I've a datatable csv of the below format - --in file format xx,xx,xx ,xx , , , , ,,xx, xxxx,, ,, xxx,... (11 Replies)
Discussion started by: dvah
11 Replies

7. Shell Programming and Scripting

Remove lines from file

Hey Gang- I have a list of servers. I want to exclude servers that begin with and end with certain characters. Is there an easy command to do this? Example wvm1234dev wvm1234pro uvm1122dev uvm1122bku uvm1344dev I want to exclude any lines that start with "wvm" OR "uvm" AND end... (7 Replies)
Discussion started by: idiotboy
7 Replies

8. Shell Programming and Scripting

Two files, remove lines from second based on lines in first

I have two files, a keepout.txt and a database.csv. They're unsorted, but could be sorted. keepout: user1 buser3 anuser19 notheruser27 database: user1,2343,"information about",field,blah,34 user2,4231,"mo info",etc,stuff,43 notheruser27,4344,"hiya",thing,more thing,423... (4 Replies)
Discussion started by: esoffron
4 Replies

9. Shell Programming and Scripting

Remove lines that are subsets of other lines in File

Hello everyone, Although it seems easy, I've been stuck with this problem for a moment now and I can't figure out a way to get it done. My problem is the following: I have a file where each line is a sequence of IP addresses, example : 10.0.0.1 10.0.0.2 10.0.0.5 10.0.0.1 10.0.0.2... (5 Replies)
Discussion started by: MisterJellyBean
5 Replies

10. Shell Programming and Scripting

awk to remove lines that do not start with digit and combine line or lines

I have been searching and trying to come up with an awk that will perform the following on a converted text file (original is a pdf). 1. Since the first two lines are (begin with) text they are removed 2. if $1 is a number then all text is merged (combined) into one line until the next... (3 Replies)
Discussion started by: cmccabe
3 Replies
IRSEND(1)							   User Commands							 IRSEND(1)

NAME
irsend - basic LIRC program to send infra-red commands SYNOPSIS
irsend [options] DIRECTIVE REMOTE CODE [CODE...] DESCRIPTION
Asks the lircd daemon to send one or more CIR (Consumer Infra-Red) commands. This is intended for remote control of electronic devices such as TV boxes, HiFi sets, etc. DIRECTIVE can be: SEND_ONCE - send CODE [CODE ...] once SEND_START - start repeating CODE SEND_STOP - stop repeating CODE LIST - list configured remote items SET_TRANSMITTERS - set transmitters NUM [NUM ...] SIMULATE - simulate IR event REMOTE is the name of a remote, as described in the lircd configuration file. CODE is the name of a remote control key of REMOTE, as it appears in the lircd configuration file. NUM is the transmitter number of the hardware device. For the LIST DIRECTIVE, REMOTE and/or CODE can be empty: LIST "" "" - list all configured remote names LIST REMOTE "" - list all codes of REMOTE LIST REMOTE CODE - list only CODE of REMOTE The SIMULATE command only works if it has been explicitly enabled in lircd. -h --help display usage summary -v --version display version -d --device use given lircd socket [/var/run/lirc/lircd] -a --address=host[:port] connect to lircd at this address -# --count=n send command n times EXAMPLES
irsend LIST DenonTuner "" irsend SEND_ONCE DenonTuner PROG-SCAN irsend SEND_ONCE OnkyoAmpli VOL-UP VOL-UP VOL-UP VOL-UP irsend SEND_START OnkyoAmpli VOL-DOWN ; sleep 3 irsend SEND_STOP OnkyoAmpli VOL-DOWN irsend SET_TRANSMITTERS 1 irsend SET_TRANSMITTERS 1 3 4 irsend SIMULATE "0000000000000476 00 OK TECHNISAT_ST3004S" FILES
/etc/lirc/lircd.conf Default lircd configuration file. It should contain all the remotes, their infra-red codes and the corresponding timing and wave- form details. DIAGNOSTICS
If lircd is not running (or /var/run/lirc/lircd lacks write permissions) irsend aborts with the following diagnostics: "irsend: could not connect to socket" "irsend: Connection refused" (or "Permission denied"). SEE ALSO
The documentation for lirc is maintained as html pages. They are located under html/ in the documentation directory. lircd(8), mode2(1), smode2(1), xmode2(1), irrecord(1), irw(1), http://www.lirc.org. irsend 0.9.0-pre1 October 2010 IRSEND(1)
All times are GMT -4. The time now is 10:59 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy