How to view a file at a specific commit/revision in git? You can use git show to view a file’s content at a specific commit in git: https://www.systutorials.com/docs/linux/man/1-git-show/ $ git show REVISION:/path/to/file You can also save a copy by $ git show REVISION:/path/to/file >file.copy
How to set the number of mappers and reducers of Hadoop in command line? Number of mappers and reducers can be set like (5 mappers, 2 reducers): -D mapred.map.tasks=5 -D mapred.reduce.tasks=2 in the command line. In the code, one can configure JobConf variables. job.setNumMapTasks(5); // 5 mappers job.setNumReduceTasks(2); // 2 reducers Note that on Hadoop…
I wanna migrate leveldb (code.google.com/p/leveldb) to my github repository. Create a new repo on github.com with this link https://help.github.com/articles/creating-a-new-repository git clone https://code.google.com/p/ project-name.git Set the remote origin url as follows: git remote set-url origin https://github.com/ username/ repo-name.git git pull to pull the latest. git push origin master after making local changes. This is the original…
The disk management tools of Windows can adjust it to some level. But there are more space available as far as I can tell. How to further adjust the system partition (C:) size of Windows? You may check these tools: EASEUS Partition Master (free) Includes Partition Manager, Disk & Partition Copy Wizard and Partition Recovery…
How to jailbreak iOS 7.1.2 on a iPhone 4s? The Pangu Jailbreak Tool ( http://en.pangu.io/ ) works like a charm for my iPhone 4S with iOS 7.1.2. Remember to back up your data before jailbreaking your iPhone.
Grub fails to boot with Windows 8 UEFI after installing Fedora 20. The Grub entry for Windows 8 is: menuentry ‘Windows Boot Manager’ { chainloader /EFI/Microsoft/Boot/bootmgfw.efi boot } How to fix it? The set root= is missing. You probably can fix this by specifying the root manually: menuentry ‘Windows Boot Manager’ { insmod part_gpt set…
How to find which hard drives a LVM volume uses to decide which volume will be affected if a disk failes. You can use lvdisplay with the –maps option to display the the mapping of logical extents to physical volumes and physical extents: # lvdisplay –maps To map physical extents to logical extents, use #…
How to erase disk partitions on U disks on Windows? Check the HDD LLF low level format tool: http://hddguru.com/software/HDD-LLF-Low-Level-Format-Tool/ It is free for personal usage. Run it as Adminiatrator and you can choose to erase partitions and MBR on the U disks. Be careful that the operation is is recoverable.
How to download a youtube video to my computer? You may use the ClipConverter.cc for downloading Youtube videos: http://www.clipconverter.cc/ How to download a YouTube video: Paste your YouTube URL at ‘Media URL’ and press Continue. Select the format and the options for the conversion. The default options are for most videos a good setting. Press…
How to replacing a string with another string with newline in Emacs? For example, to replace: good editor with good editor: Emacs What you need is actually to input a newline in Emacs: C-q C-j C-q is for quoted-insert, and C-j is a newline (0xa).
How to make emacs remember last editing positions in files. It will be convenient next time I open the same file the cursor automatically moves to the position I was last time editing the same file. The behavior seems enabled by default in Vim. How to make Emacs do this? I use the saveplace mode….
SSH tunnel and port forwarding is great and convenient to use. But is it possible to set up a VPN like connection over SSH? If you are on Linux or Mac, you can use sshuttle: https://github.com/apenwarr/sshuttle If you are on Windows, you can use ProxyCap: http://www.proxycap.com/index.html Both are great software.
One of the most common causes of UDP data gram lost on Linux is an undersized receive buffer on the Linux socket. How to enlarge Linux UDP buffer size? On Linux, you can change the UDP buffer size (e.g. to 26214400) by (as root): sysctl -w net.core.rmem_max=26214400 The default buffer size on Linux is 131071….
I have a mp4 video file. How to embed it video in HTML pages? I use this piece of code: In HTML: <video class=”movie” src=”path/to/file.mp4″ controls></video> The CSS for “movie” class: .movie { max-width:1000px; } Here is one example.
How to mark a line as deleted in BBCode? e.g. a line crossing through the text. You can use the [s] tag. The BBCode: [s]strikethrough text[/s] will be converted <s>strikethrough text</s>, <del>strikethrough text</del> or <span style=”text-decoration: line-through;”>strikethrough text</span> Check more at: http://en.wikipedia.org/wiki/BBCode
Sometimes the commands’ output have some non-printable ASCII characters. How to filter away these non-printable ASCII characters on Linux? You can consider the problem as “how to leave only printable ascii characters?”. The printable characters in ASCII table are: Octal 011: Tab Octal 012: Line Feed Octal 015: Carriage Return Octal 040 to 176: printable…
How to calculate the average of value in lines of a text file on Linux by a script? The file.txt is like: Run 0: Time used: 22.235331711 seconds. Run 1: Time used: 20.784491219 seconds. Run 2: Time used: 21.851638876 seconds. What I want it to calculate the average time. awk is handy for this purpose:…
sbt‘s log level can be set by execute set logLevel := Level.Error inside sbt. How to set the sbt log level at the command line? Add –error to sbt for specify the logLevel to error: sbt –error “your command”
Tutorials on how to create patches and apply patches with git. A nice tutorial: https://ariejan.net/2009/10/26/how-to-create-and-apply-a-patch-with-git/ Manuals: git format-patch: https://www.systutorials.com/docs/linux/man/1-git-format-patch/git apply: https://www.systutorials.com/docs/linux/man/1-git-apply/
How to install multiple versions of sbt on my Linux host For example, some projects use 0.12.x while some use 0.13.x. Installing neither in the system only is not sufficient enough. You may use the excellent sbt-extras: https://github.com/paulp/sbt-extras Most of the time, it detects the version of sbt needed in the project direoctory automatically: [zma@office…