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 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”
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…
How to package a Scala project to a .jar file with sbt? Manually packaging the .class files are fine but too tedious. A jar of just the project classes The command: sbt package will produces the main artifact as a jar into target/scala-2.x.y/project_name_2.x.y-zz.jar. Continuously building the package: sbt ~package Standalone jar with all dependencies If…
I know that gettimeofday() is a nice API. But how to get the number of seconds with milliseconds since the epoch time? You can get the time at nano-seconds level (although it is not guaranteed that the last digits are accurate) by: date +%s.%N
How to catch the kill signals sent by the kill command in C programs on Linux? For example, I have a daemon progd running, and will kill it by: pkill progd The question is how to catch the signal sent by the kill command and response to it in the progd program implemented in C…
How to force ibus to restart in Gnome 3? There used to be a menu. But it does not provide the restart option anymore. To kill current ibus daemon: pkill -o ibus-daemon To start a new ibus daemon in Gnome 3, run this command in “Enter a command” tool by Alt+F2: /usr/bin/ibus-daemon –replace –xim –panel…
How to make Emacs highlighting part of lines that go over 80 chars? I use the whitespace mode: ;; `lines-tail`, highlight the part that goes beyond the ;; limit of `whitespace-line-column` (require ‘whitespace) (setq whitespace-style ‘(face empty tabs lines-tail trailing)) (global-whitespace-mode t) More: https://github.com/zma/emacs-config/blob/master/.emacs Alternatively, you can run highlight-lines-matching-regexp with the expression .{81}. http://stackoverflow.com/questions/6344474/how-can-i-make-emacs-highlight-lines-that-go-over-80-chars
How to run Chrome on remote host over a SSH tunnel? This way, I can access resource that can only be accessed inside the remote host’s network. Running Chrome over a SSH tunnel is much easier than running Firefox over SSH from a Linux host: First, ssh to the remote host with -X option: ssh…
How to replace tabs with spaces in Emacs? You can first select the regions of text for converting/replacing, then run M-x untabify to replace all tabs with appropriate number of spaces. There is also a M-x tabify for replacing sequences of spaces to tabs. There are also commands to convert tabs to spaces or vice…
The sort command has a -n option to sort a file by numbers. However, it does not work with hexadecimal numbers. For example, this file: 400000000 __crt0 400000039 __newr0 400001B14 get_my_task_id 400001C14 get_new_task_id 400001582 input_char 40000166E input_q 400001A5D input_q_exit 400002002 main 4000000DB output_char 400001134 output_char_str 40000100C output_id 40000018F output_q 400000614 output_q_digits 400000B7E output_q_hex 400000D3E output_q_hex_j1…
How to get a tree-like view of the git commit history? My favorite command line: git log –graph –oneline It will prints a text based graph like (with colors): * b5dc8b9 Merge branch ‘master’ of https://github.com/layerzero/libi0 | | * 7514ef1 revised the README.md a little bit | * 6692428 align size to page for both…
crond sends email notifications automatically. However, these emails are not needed. How to disabled it? If your command does not anything printed to STDOUT or STDERR, there is not emails send. You can redirect 2 and 1 to /dev/null at the end of your command. You can also set the MAILTO variable to empty by…
On Linux, how to download a webpage as a mobile browser? You can change the agent of curl to be a mobile browser’s and the remote webserver may be consider the request from a mobile browser: curl -A “Mozilla/5.0 (iPhone; CPU iPhone OS 6_1_3 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) CriOS/28.0.1500.12 Mobile/10B329 Safari/8536.25″…
How to find which files are opened by a Linux program? For example, when I run cat ~/.bashrc, how to find out which files are opened by cat? You can achieve this by using strace if the program “open” files using system calls. For example, I run as this: strace -o /tmp/st cat ./.bashrc grep…
How to convert a latex document with figures to a HTML file? htlatex (On Fedora, it is in the package texlive-tex4ht) can generate the html from a latex doc better than latex2html. From my experience, it can produce a better html file.
How to rearrange Alt, Ctrl and Win keys on Linux: Win as Alt and Ctrl/Alt as Ctrl? On Linux, the Win key is seldom used. Mapping the Alt keys which are close to my thumb is damn convenient for Emacs users. Hence, the keyboard at the bottom line would look like: ———————————————————— |Ctrl|Alt|Ctrl| Space Bar…
How to get the correct classpath for compiling MapReduce jobs on Hadoop 2.2.0 (YARN)? The yarn command from Hadoop 2 can find it out for you: yarn classpath You may add the full path to yarn which is under bin directory of the Hadoop distribution pachage, if it is not in your $PATH.
How to split a text file by lines on Linux? For example, to split a file content.txt into many files and each split contains 1024 lines. You can use the split command on Linux: split -l 1024 content.txt splitted-content.txt- It will generate splitted-content.txt-{aa,ab,….}