Last updated on May 5, 2021

Desktop email clients, such asThunderbird andClaws Mail, are preferred over their web counterparts by many professionals and power users due to their additional convenience and security. However, one big downside is that they often expose the sender's IP address to the receivers, since many SMTP servers record the sender's IP address and put it in the header, something similar toReceived: from [xxx.xxx.xxx.xxx] (my.example.com. [xxx.xxx.xxx.xxx]). This, unfortunately, puts the sender's privacy in great jeopardy, as an IP address can reveal so much information including location, ISP, and institution names.

To address this issue, one simple solution is to let the email client connect via a proxy. While a system-widely available proxy works for many users, some of us just want our email clients, but not other programs, to go through a specific proxy. In this post, I'll demonstrate how to use an email client automatically via SSH tunneling. The instructions are specifically tailored for GNU/Linux and MacOS users, as it involves some uses of UNIX commands and bash scripts; if you are on Windows, you can still follow the instructions with the help ofCygwin.

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Last updated on August 8, 2017

Pip is a package management system for installing and managing Python software packages. To enable auto completion forpip in zsh, thedocumentation of pip suggests adding the following line to~/.zshrc:

eval "`pip completion --zsh`"

However, merely having this line would not enable auto completion forpip3. To enable auto completion forpip3 as well, add the following line after the line above:

compctl -K _pip_completion pip3

Last updated on October 28, 2018

Libinput is a library to handle input devices inWayland andX.Org. It can be used as a drop-in replacement for evdev and synaptics in X.Org, and it is supported by a wide range of desktop environments, including GNOME and Xfce. In this post, we will see how to enable natural scrolling for trackpads using libinput. We will also leave mouses alone, i.e., no natural scrolling for mouses.

First, we need to know the name of the trackpad to enable natural scrolling for. This can be easily known by executingxinput --list. My output includes the following:

⎡ Virtual core pointer                          id=2    [master pointer  (3)]⎜   ↳ Virtual core XTEST pointer                id=4    [slave  pointer  (2)]⎜   ↳ bcm5974                                   id=13   [slave  pointer  (2)]

It is easy to see that my trackpad isbcm5974.

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Last updated on December 13, 2016

Themake utility is an standard utility on POSIX systems (GNU/Linux, macOS, etc.) that update files derived from other files, such as compiling source files to their binary forms. It is widely supported and used across different fields such as organizing and building C/C++/Fortran projects, buildingSphinx documentation, etc.

The most popular implementation of the make utility is probablyGNU make, which is usually the default make program on various GNU/Linux distributions. (On macOS, the version of the default GNU make is pretty old. Please consultInstall and Use GNU Command Line Tools on macOS/OS X for a newer version.) It adds one very important feature besides the standard make specification: parallelization. The command line option-j can be used to specify the maximum number of jobs that it is allowed to run simultaneously. However, it is quite annoying to type up this option every time when using it—we want a setting such that the CPU can be fully utilized by default. To achieve this goal, add the following lines to your~/.bashrc if you use bash or~/.zshrc if you use zsh:

# set MAKEFLAGSif type nproc &>/dev/null; then   # GNU/Linux  export MAKEFLAGS="$MAKEFLAGS -j$(($(nproc)-1))"elif type sysctl -n hw.ncpu &>/dev/null; then   # macOS, FreeBSD  export MAKEFLAGS="$MAKEFLAGS -j$(($(sysctl -n hw.ncpu)-1))"fi

The code above sets the envrionmental variableMAKEFLAGS, which specifies the command line arguments of any invoked make subprocesses. It is set such that the maximum number of jobs that is allowed to be run simultaneously is equal to the number of available CPU cores minus 1. In this way, the hardware is more or less fully utilized when using make, with one CPU core left for other potential tasks on the system.

Last updated on April 14, 2024

Thels command is a command to list files on a UNIX-like system. It is probably one of the most used command. However, a plainls command without any polishing may look really “plain”. Here, we will slightly configure this command to make it more usable:

• More colorful output
• Automatic pagination for long file lists
• File type indication
• Human readable sizes
• Natural ordering of files

Screenshots:

Output ofls before configuration

Output ofls after configuration

Pagination forls

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Last updated on December 10, 2016

In both bash and zsh, there are multiple methods to check whether a command exists. In this post, a set of speed tests will be performed on them to find the fastest way in each of the two shells (NOT to compare the two shells). We will test 5 different methods (foobar is the command to test for existence in the list):

• type foobar &> /dev/null
• hash foobar &> /dev/null
• command -v foobar &> /dev/null
• which foobar &> /dev/null
• (( $+commands[foobar] )) (zsh only)

All the methods listed above will have a return status of zero if the commandfoobar exists, otherwise non-zero. That is, after replacingtesting-command by any of the commands listed above, you can test the existence of the commandfoobar by executingtesting-command && echo exist || echo non-exist.

Throughout this post,ls will be the command that is used for testing existence, which does exist on the system which runs the tests. The test environment is Debian Jessie with bash 4.3.30 and zsh 5.0.7 on Intel Xeon processor E3-1240 v3 (8 MB Cache, 3.4 GHz). The test scripts are also available at the end of the post.

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Last updated on December 10, 2016

Inzsh, it is often annoying that we can't easily restore the command we just canceled byCtrl-C: canceled commands are not recorded into the history file and thus cannot be restored by searching previous commands. To make the restoration possible, zsh provides a variableZLE_LINE_ABORTED which keeps a record of the last command that was canceled—everything looks so simple. However, for some reasons, such as canceling stuck tab completion, we often pushCtrl-C for more than once—butZLE_LINE_ABORTED would become empty ifCtrl-C is used on an empty line! Thanks to the great extensibility of zsh, we can solve this issue by tweakingzle-line-init (add the following to your~/.zshrc):

function zle-line-init {  # Your other zle-line-init configuration ...  # Store the last non-empty aborted line in MY_LINE_ABORTED  if [[ -n $ZLE_LINE_ABORTED ]]; then    MY_LINE_ABORTED="$ZLE_LINE_ABORTED"  fi  # Restore aborted line on the first undo.  if [[ -n $MY_LINE_ABORTED ]]; then    local savebuf="$BUFFER" savecur="$CURSOR"    BUFFER="$MY_LINE_ABORTED"    CURSOR="$#BUFFER"    zle split-undo    BUFFER="$savebuf" CURSOR="$savecur"  fi}zle -N zle-line-init

• Line 1: Define thezle-line-init widget which will be executed every time when the a new command line is ready to take input.
• Line 5-7: IfZLE_LINE_ABORTED is non-empty, save it toMY_LINE_ABORTED.
• Line 10-16: IfMY_LINE_ABORTED is non-empty, the initial undo will restore the contents inMY_LINE_ABORTED. Also seeman zshzle for an explanation ofsplit-undo.
• Line 18: Install the widgetzle-line-init.

Now type any command and pushCtrl-C twice and undo (bound toCtrl-/ by default): your canceled command is back!

Note that if you usezsh-autosuggestions this code snippet somehow breaks it. Adding_zsh_autosuggest_widget_clear before the end ofzle-line-init would fix it.

References

• Tip of the day: restoring an aborted command-line (Zsh mailing list)
• ZLE_LINE_ABORTED: how to restore the last non-blank aborted line? (Zsh mailing list)

Last updated on December 25, 2024

Due to its speed and simplicity,GNUless is probably the most common defaultterminal pager on various GNU/Linux distributions—you may have probably used it explicitly via theless command, or implicitly when you execute theman command orgit diff. Although the default configuration ofless does not really offer much except for a basic text viewer, it is actually much more powerful than most people think. Here a few improvements over the default configuration are offered.

For macOS/OS X users: consider installing a newer version ofless and other GNU command line utilities. To do so, you can follow the instructionshere.

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Last updated on December 10, 2016

It is well known that long matching lines returned by grep is often disturbing. For example, a simple grep on a bootstrap javascript filebootstrap.min.js can cause a crazy tragedy—one single matching line can occupy a number of lines in the terminal:

How can we solve this issue?

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Last updated on October 9, 2016

As one of the most popular package manager on OS X,Homebrew is indeed a very nice tool to manage packages. However, when you want to back up your packages, or migrate the packages onto another machine, Homebrew didn’t invent such a tool. If you are moving to an OS X of the same version, you can simply copy the Homebrew directory (default is/usr/local) to your new machine. Otherwise, we need to find a way to install the exactly same packages on your new machine. In order to accomplish the goal, I wrote a small piece of bash script to generate a restore script to install the packages.

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