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  • Oneliner-question

    - by sid_com
    I proudly present a solution to the problem: perl -00 -F"\n" -anE '$_ = ( split / /, $F[1] )[0]; if ( !/error/ ) { $sum += $_; $c++ } } { say $sum / $c' file The problem: the first field of the second line of each paragraph if it is not error. How could I do this without the paragraph-mode? perl -anE 'say $F[0] if not /error/ and the second /\S+/ after /^$/' file

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  • Recursively rename files - oneliner preferably

    - by zetah
    I found this answer how do i... but it simply doesn't work - it did not rename any file for unknown to me reason Before I started to search around I thought that it should be easy task even for novice penguin, but it doesn't seem so for me. For example, I simply can't tell ls to list all *.txt in all subfolders, which was surprise to me (without grep or similar). Then I found find and find . -name name_1.txt lists files fine, but for f in $(find . -name name_1.txt) ; do echo "$f" ; done splits whole file paths with space as separator, so it's unusable to pass that output to some command like mv or rename I want to ask whats wrong with above command and if possible some nifty oneliner so I can recursively rename name_1.txt to name_2.txt

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  • Oneliner to count the number of tabs in each line of a file

    - by JasonHorner
    I have a file that is tab delimited. I would like a powershell script that counts the number of tabs in each line. I came up with this: ${C:\tabfile.txt} |% {$_} | Select-String \t | Measure-Object | fl count it yields 3, Which is the number of lines in the file. any pointers to what I'm doing wrong? I would like it to print a single number for each line in the file.

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  • Quickly read pgm header with comments in C

    - by Vi
    Quickly write PGM header is fprintf(f, "P5 %d %d 255\n", width, height); Quickly read PGM header is fscanf(f, "P5%d%d%*d\n"); // now can read the data from f, but it fails when the header contains comments (like if saved by GIMP). How to read PGM header in more compatible way (without a lot of code or extra dependencies, I don't want my program to cease being oneliner because of this)?

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  • version of ldap installed - one liner

    - by PJ
    HI, I am using LDAP which is installed in a solaris machine. To check the version of LDAP i go to /ldap and check the version installed as if it is version 5 then there is a directory of the name v5.0 and so on. After getting into the directory i check the directory structure. Can anybody tell me is there any shortest way or one liner to check the version of ldap installed in my machine. Thanks in advance.

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  • replacing a path with sed

    - by compie
    How can I use sed to replace this line char * path_list_[1] = { "/some/random/path" }; with this line char * path_list_[2] = { "lib/foo", "lib/bar" }; in a file named source.c Notes: * The path is really random. * Your solution should only change this line in source.c * I'm only interested in a sed oneliner. You can use this Python regex as a starting point: text = re.sub('static const char \* path_list_\[1\] = \{ "[^"]*" \};', 'static const char * path_list_[2] = { "lib/sun", "lib/matlab" };', text)

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  • Calculate disk space occupied by many .png files

    - by Alexander Farber
    I have 357 .png files located in different sub dirs of the current dir: settings# find . -name \*.png |wc -l 357 settings# find . -name \*.png | head ./assets/authenticationIcons/audio.png ./assets/authenticationIcons/bbid.png ./assets/authenticationIcons/camera.png ./bin/icons/ca_video_chat.png ./bin/icons/ca_voice_control.png ./bin/icons/ca_vpn.png ./bin/icons/ca_wifi.png Is there a oneliner to calculate the total disk space occupied by them (before I pngcrush them)? I've tried (unsuccessfully): settings# find . -name \*.png | xargs du -s 4 ./assets/support/wifi_locked_icon_white.png 1 ./assets/support/wifi_vpn_icon_connected.png 1 ./assets/support/wi_fi.png 1 ./assets/support/wi_fi_conected.png 8 ./bin/blackberry-tablet-icon.png 2 ./bin/icons/ca_about.png 2 ./bin/icons/ca_accessibility.png 2 ./bin/icons/ca_accounts.png 2 ./bin/icons/ca_airplane_mode.png 2 ./bin/icons/ca_application_permissions.png 1 ./bin/icons/ca_balance.png

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  • bash pipe construct to prepend something to the stdoutput of previous command

    - by AndreasT
    I want to use sendmail to send me stuff and want to do it in a oneliner. echo "mail content" | sendmail emailataddres.com Sends it without subject. The subject line must come before the Mail content, so I am looking for something along the lines of: echo "mail content" | prepend "Subject: All that matters" | sendmail emailataddres.com sed and awk tend to be really awkward to use and remember. EDIT:Just to clarify: echo "Mail content" is just an illustrating example. I need to be able to prepend stuff to stdout streams from any source. e.g.: ifconfig, zcat, etc..

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  • List/remove files, with filenames containing string that's "more than a month ago"?

    - by Martin Tóth
    I store some data in files which follow this naming convention: /interesting/data/filename-YYYY-MM-DD-HH-MM How do I look for the ones with date in file name < now - 1 month and delete them? Files may have changed since they were created, so searching according to last modification date is not good. What I'm doing now, is filter-ing them in python: prefix = '/interesting/data/filename-' import commands names = commands.getoutput('ls {0}*'.format(prefix)).splitlines() from datetime import datetime, timedelta all_files = map(lambda name: { 'name': name, 'date': datetime.strptime(name, '{0}%Y-%m-%d-%H-%M'.format(prefix)) }, names) month = datetime.now() - timedelta(days = 30) to_delete = filter(lambda item: item['date'] < month, all_files) import os map(os.remove, to_delete) Is there a (oneliner) bash solution for this?

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  • how to check if something is in the queue of torque?

    - by kloop
    I want to re-run some jobs that completed prematurely under torque. These jobs are run through .job scripts (using qsub). However, I don't want to re-run a job which is already in the queue. Given a script filename, how can I know whether it is already in torque's queue (using qstat?) or not? I prefer to do it programmatically, of course, so any oneliner that searches for a given script name would be great. I will note that I can grep submit_args in qstat -f, but I can't get it to display the whole script name when it is too long. This is crucial. EDIT: I managed to solve it using the following command: qstat -x | perl -pi -e 's/\<\//\n/g' | grep job$ | grep -v submit_args | perl -pi -e 's/Job_Id\>\<Job_Name\>//' works because all my scripts end in the string "job".

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  • Filtering and copying with PowerShell

    - by Bergius
    In my quest to improve my PowerShell skills, here's an example of an ugly solution to a simple problem. Any suggestions how to improve the oneliner are welcome. Mission: trim a huge icon library down to something a bit more manageable. The original directory structure looks like this: /Apps and Utilities /Compile /32 Bit Alpha png /Compile 16 n p.png /+ 10 or more files /+ 5 more formats with 10 or more files each /+ 20 or so icon names /+ 22 more categories I want to copy the 32 Bit Alpha pngs and flatten the directory structure a bit. Here's my quick and very dirty solution: $dest = mkdir c:\icons; gci -r | ? { $_.Name -eq '32 Bit Alph a png' } | % { mkdir ("$dest\" + $_.Parent.Parent.Name + "\" + $_.Parent.Name); $_ } | gci | % { cp $_. FullName -dest ("$dest\" + $_.Directory.Parent.Parent + "\" + $_.Directory.Parent) } Not nice, but it solved my problem. Resulting structure: /Apps and Utilities /Compile /Compile 16 n p.png /etc /etc /etc How would you do it?

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  • Replace CR/LF in a text file only after a certain column

    - by Olav
    I have a large text file I would like to put on my ebook-reader, but the formatting becomes all wrong because all lines are hard wrapped at or before column 80 with CR/LF, and paragraphs/headers are not marked differently, only a single CR/LF there too. What I would like is to replace all CR/LF's after column 75 with a space. That would make most paragraphs continuous. (Not a perfect solution, but a lot better to read.) Is it possible to do this with a regex? Preferably a (linux) perl or sed oneliner, alternatively a Notepad++ regex.

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  • ps forrest for session id

    - by azatoth
    Often I want to get a nice readout what process are running and their relationship; I usually by habit runs ps auxfww and eventual grep for the process in question. Having been thinking about the problem I tried to create an oneliner to get the process tree in ps ufww format for all processes which has the session id specified by arbitrary process name(s); ending up in following code: ps ufww --sid=$(ps -C apache2 -o sess --no-headers | sort | uniq | grep -v -E '^ +0$' | awk 'NR==1{x=$0;next}NF{x=x","$0};END{gsub(/[[:space:]]*/,"",x);print x}') giving for example following output: USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 4157 0.0 0.1 41264 3120 ? Ss Jun11 0:00 /usr/sbin/apache2 -k start www-data 4329 0.0 0.0 41264 1976 ? S Jun11 0:00 \_ /usr/sbin/apache2 -k start www-data 4330 0.0 0.0 41264 2028 ? S Jun11 0:00 \_ /usr/sbin/apache2 -k start www-data 4331 0.0 0.0 41264 2028 ? S Jun11 0:00 \_ /usr/sbin/apache2 -k start www-data 4332 0.0 0.0 41264 2028 ? S Jun11 0:00 \_ /usr/sbin/apache2 -k start www-data 4333 0.0 0.0 41264 2032 ? S Jun11 0:00 \_ /usr/sbin/apache2 -k start www-data 6648 0.0 0.0 41264 1884 ? S Jun11 0:00 \_ /usr/sbin/apache2 -k start www-data 6654 0.0 0.0 41264 1884 ? S Jun11 0:00 \_ /usr/sbin/apache2 -k start www-data 6655 0.0 0.0 41264 1884 ? S Jun11 0:00 \_ /usr/sbin/apache2 -k start I do wonder now if anyone has an better idea to solve this issue? Are there anything out there that is easier to "oneline" and gives above or better information? For example I would actually want to have included all childs relative any parent. (uncertain if this should be on SF instead, but felt it was more like an programming question)

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  • How to remove lowercase sentence fragments from text?

    - by Aaron
    Hello: I'm tyring to remove lowercase sentence fragments from standard text files using regular expresions or a simple Perl oneliner. These are commonly referred to as speech or attribution tags, for example - he said, she said, etc. This example shows before and after using manual deletion: Original: "Ah, that's perfectly true!" exclaimed Alyosha. "Oh, do leave off playing the fool! Some idiot comes in, and you put us to shame!" cried the girl by the window, suddenly turning to her father with a disdainful and contemptuous air. "Wait a little, Varvara!" cried her father, speaking peremptorily but looking at them quite approvingly. "That's her character," he said, addressing Alyosha again. "Where have you been?" he asked him. "I think," he said, "I've forgotten something... my handkerchief, I think.... Well, even if I've not forgotten anything, let me stay a little." He sat down. Father stood over him. "You sit down, too," said he. All lower case sentence fragments manually removed: "Ah, that's perfectly true!" "Oh, do leave off playing the fool! Some idiot comes in, and you put us to shame!" "Wait a little, Varvara!" "That's her character," "Where have you been?" "I think," "I've forgotten something... my handkerchief, I think.... Well, even if I've not forgotten anything, let me stay a little." He sat down. Father stood over him. "You sit down, too," I've changed straight quotes " to balanced and tried: ” (...)+[.] Of course, this removes some fragments but deletes some text in balanced quotes and text starting with uppercase letters. [^A-Z] didn't work in the above expression. I realize that it may be impossible to achieve 100% accuracy but any useful expression, perl, or python script would be deeply appreciated. Cheers, Aaron

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  • DTracing TCP congestion control

    - by user12820842
    In a previous post, I showed how we can use DTrace to probe TCP receive and send window events. TCP receive and send windows are in effect both about flow-controlling how much data can be received - the receive window reflects how much data the local TCP is prepared to receive, while the send window simply reflects the size of the receive window of the peer TCP. Both then represent flow control as imposed by the receiver. However, consider that without the sender imposing flow control, and a slow link to a peer, TCP will simply fill up it's window with sent segments. Dealing with multiple TCP implementations filling their peer TCP's receive windows in this manner, busy intermediate routers may drop some of these segments, leading to timeout and retransmission, which may again lead to drops. This is termed congestion, and TCP has multiple congestion control strategies. We can see that in this example, we need to have some way of adjusting how much data we send depending on how quickly we receive acknowledgement - if we get ACKs quickly, we can safely send more segments, but if acknowledgements come slowly, we should proceed with more caution. More generally, we need to implement flow control on the send side also. Slow Start and Congestion Avoidance From RFC2581, let's examine the relevant variables: "The congestion window (cwnd) is a sender-side limit on the amount of data the sender can transmit into the network before receiving an acknowledgment (ACK). Another state variable, the slow start threshold (ssthresh), is used to determine whether the slow start or congestion avoidance algorithm is used to control data transmission" Slow start is used to probe the network's ability to handle transmission bursts both when a connection is first created and when retransmission timers fire. The latter case is important, as the fact that we have effectively lost TCP data acts as a motivator for re-probing how much data the network can handle from the sending TCP. The congestion window (cwnd) is initialized to a relatively small value, generally a low multiple of the sending maximum segment size. When slow start kicks in, we will only send that number of bytes before waiting for acknowledgement. When acknowledgements are received, the congestion window is increased in size until cwnd reaches the slow start threshold ssthresh value. For most congestion control algorithms the window increases exponentially under slow start, assuming we receive acknowledgements. We send 1 segment, receive an ACK, increase the cwnd by 1 MSS to 2*MSS, send 2 segments, receive 2 ACKs, increase the cwnd by 2*MSS to 4*MSS, send 4 segments etc. When the congestion window exceeds the slow start threshold, congestion avoidance is used instead of slow start. During congestion avoidance, the congestion window is generally updated by one MSS for each round-trip-time as opposed to each ACK, and so cwnd growth is linear instead of exponential (we may receive multiple ACKs within a single RTT). This continues until congestion is detected. If a retransmit timer fires, congestion is assumed and the ssthresh value is reset. It is reset to a fraction of the number of bytes outstanding (unacknowledged) in the network. At the same time the congestion window is reset to a single max segment size. Thus, we initiate slow start until we start receiving acknowledgements again, at which point we can eventually flip over to congestion avoidance when cwnd ssthresh. Congestion control algorithms differ most in how they handle the other indication of congestion - duplicate ACKs. A duplicate ACK is a strong indication that data has been lost, since they often come from a receiver explicitly asking for a retransmission. In some cases, a duplicate ACK may be generated at the receiver as a result of packets arriving out-of-order, so it is sensible to wait for multiple duplicate ACKs before assuming packet loss rather than out-of-order delivery. This is termed fast retransmit (i.e. retransmit without waiting for the retransmission timer to expire). Note that on Oracle Solaris 11, the congestion control method used can be customized. See here for more details. In general, 3 or more duplicate ACKs indicate packet loss and should trigger fast retransmit . It's best not to revert to slow start in this case, as the fact that the receiver knew it was missing data suggests it has received data with a higher sequence number, so we know traffic is still flowing. Falling back to slow start would be excessive therefore, so fast recovery is used instead. Observing slow start and congestion avoidance The following script counts TCP segments sent when under slow start (cwnd ssthresh). #!/usr/sbin/dtrace -s #pragma D option quiet tcp:::connect-request / start[args[1]-cs_cid] == 0/ { start[args[1]-cs_cid] = 1; } tcp:::send / start[args[1]-cs_cid] == 1 && args[3]-tcps_cwnd tcps_cwnd_ssthresh / { @c["Slow start", args[2]-ip_daddr, args[4]-tcp_dport] = count(); } tcp:::send / start[args[1]-cs_cid] == 1 && args[3]-tcps_cwnd args[3]-tcps_cwnd_ssthresh / { @c["Congestion avoidance", args[2]-ip_daddr, args[4]-tcp_dport] = count(); } As we can see the script only works on connections initiated since it is started (using the start[] associative array with the connection ID as index to set whether it's a new connection (start[cid] = 1). From there we simply differentiate send events where cwnd ssthresh (congestion avoidance). Here's the output taken when I accessed a YouTube video (where rport is 80) and from an FTP session where I put a large file onto a remote system. # dtrace -s tcp_slow_start.d ^C ALGORITHM RADDR RPORT #SEG Slow start 10.153.125.222 20 6 Slow start 138.3.237.7 80 14 Slow start 10.153.125.222 21 18 Congestion avoidance 10.153.125.222 20 1164 We see that in the case of the YouTube video, slow start was exclusively used. Most of the segments we sent in that case were likely ACKs. Compare this case - where 14 segments were sent using slow start - to the FTP case, where only 6 segments were sent before we switched to congestion avoidance for 1164 segments. In the case of the FTP session, the FTP data on port 20 was predominantly sent with congestion avoidance in operation, while the FTP session relied exclusively on slow start. For the default congestion control algorithm - "newreno" - on Solaris 11, slow start will increase the cwnd by 1 MSS for every acknowledgement received, and by 1 MSS for each RTT in congestion avoidance mode. Different pluggable congestion control algorithms operate slightly differently. For example "highspeed" will update the slow start cwnd by the number of bytes ACKed rather than the MSS. And to finish, here's a neat oneliner to visually display the distribution of congestion window values for all TCP connections to a given remote port using a quantization. In this example, only port 80 is in use and we see the majority of cwnd values for that port are in the 4096-8191 range. # dtrace -n 'tcp:::send { @q[args[4]-tcp_dport] = quantize(args[3]-tcps_cwnd); }' dtrace: description 'tcp:::send ' matched 10 probes ^C 80 value ------------- Distribution ------------- count -1 | 0 0 |@@@@@@ 5 1 | 0 2 | 0 4 | 0 8 | 0 16 | 0 32 | 0 64 | 0 128 | 0 256 | 0 512 | 0 1024 | 0 2048 |@@@@@@@@@ 8 4096 |@@@@@@@@@@@@@@@@@@@@@@@@@@ 23 8192 | 0

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  • How to begin? Windows 8 Development

    - by Dennis Vroegop
    Ok. I convinced you in my last post to do some Win8 development. You want a piece of that cake, or whatever your reasons may be. Good! Welcome to the club! Now let me ask you a question: what are you going to write? Ah. That’s the big one, isn’t it? What indeed? If you have been creating applications for computers before you’re in for quite a shock. The way people perceive apps on a tablet is quite different from what we know as applications. There’s a reason we call them apps instead of applications! Yes, technically they are applications but we don’t call them apps only because it sounds cool. The abbreviated form of the word applications itself is a pointer. Apps are small. Apps are focused. Apps are more lightweight. Apps do one thing but they do that one thing extremely good. In the ‘old’ days we wrote huge systems. We build ecosystems of services, screens, databases and more to create a system that provides value for the user. Think about it: what application do you use most at work? Can you in one sentence describe what it is, or what it does and yet still distinctively describe its purpose? I doubt you can. Let’s have a look at Outlouk. We all know it and we all love or hate it. But what is it? A mail program? No, there’s so much more there: calendar, contacts, RSS feeds and so on. Some call it a ‘collaboration’  application but that’s not really true as well. After all, why should a collaboration application give me my schedule for the day? I think the best way to describe Outlook is “client for Exchange”  although that isn’t accurate either. Anyway: Outlook is a great application but it’s not an ‘app’ and therefor not very suitable for WinRT. Ok. Disclaimer here: yes, you can write big applications for WinRT. Some will. But that’s not what 99.9% of the developers will do. So I am stating here that big applications are not meant for WinRT. If 0.01% of the developers think that this is nonsense then they are welcome to go ahead but for the majority here this is not what we’re talking about. So: Apps are small, lightweight and good at what they do but only at that. If you’re a Phone developer you already know that: Phone apps on any platform fit the description I have above. If you’ve ever worked in a large cooperation before you might have seen one of these before: the Mission Statement. It’s supposed to be a oneliner that sums up what the company is supposed to do. Funny enough: although this doesn’t work for large companies it does work for defining your app. A mission statement for an app describes what it does. If it doesn’t fit in the mission statement then your app is going to get to big and will fail. A statement like this should be in the following style “<your app name> is the best app to <describe single task>” Fill in the blanks, write it and go! Mmm.. not really. There are some things there we need to think about. But the statement is a very, very important one. If you cannot fit your app in that line you’re preparing to fail. Your app will become to big, its purpose will be unclear and it will be hard to use. People won’t download it and those who do will give it a bad rating therefor preventing that huge success you’ve been dreaming about. Stick to the statement! Ok, let’s give it a try: “PlanesAreCool” is the best app to do planespotting in the field. You might have seen these people along runways of airports: taking photographs of airplanes and noting down their numbers and arrival- and departure times. We are going to help them out with our great app! If you look at the statement, can you guess what it does? I bet you can. If you find out it isn’t clear enough of if it’s too broad, refine it. This is probably the most important step in the development of your app so give it enough time! So. We’ve got the statement. Print it out, stick it to the wall and look at it. What does it tell you? If you see this, what do you think the app does? Write that down. Sit down with some friends and talk about it. What do they expect from an app like this? Write that down as well. Brainstorm. Make a list of features. This is mine: Note planes Look up aircraft carriers Add pictures of that plane Look up airfields Notify friends of new spots Look up details of a type of plane Plot a graph with arrival and departure times Share new spots on social media Look up history of a particular aircraft Compare your spots with friends Write down arrival times Write down departure times Write down wind conditions Write down the runway they take Look up weather conditions for next spotting day Invite friends to join you for a day of spotting. Now, I must make it clear that I am not a planespotter nor do I know what one does. So if the above list makes no sense, I apologize. There is a lesson: write apps for stuff you know about…. First of all, let’s look at our statement and then go through the list of features. Remove everything that has nothing to do with that statement! If you end up with an empty list, try again with both steps. Note planes Look up aircraft carriers Add pictures of that plane Look up airfields Notify friends of new spots Look up details of a type of plane Plot a graph with arrival and departure times Share new spots on social media Look up history of a particular aircraft Compare your spots with friends Write down arrival times Write down departure times Write down wind conditions Write down the runway they take Look up weather conditions for next spotting day Invite friends to join you for a day of spotting. That's better. The things I removed could be pretty useful to a plane spotter and could be fun to write. But do they match the statement? I said that the app is for spotting in the field, so “look up airfields” doesn’t belong there: I know where I am so why look it up? And the same goes for inviting friends or looking up the weather conditions for tomorrow. I am at the airfield right now, looking through my binoculars at the planes. I know the weather now and I don’t care about tomorrow. If you feel the items you’ve crossed out are valuable, then why not write another app? One that says “SpotNoter” is the best app for preparing a day of spotting with my friends. That’s a different app! Remember: Win8 apps are small and very good at doing ONE thing, and one thing only! If you have made that list, it’s time to prepare the navigation of your app. The navigation is how users see your app and how they use it. We’ll do that next time!

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