Author: ersi

On GNU/Linux, a highly useful command for beginners is man. It means “manual” and it’s the documentation and tutorial that comes with the installed operating system.

About man pages

Man pages are accessed by typing man cmd where ‘cmd’ is a command that the user wants to know more about. For example try man cp.

A command that does not exist will result in this:

~$ man cmd No manual entry for cmd 

Unfortunately, not all commands and programs have man pages. Some are missing, because they are not installed in the operating system. (In this case, read about them online.) Some are missing, because they were never written. (In this case, cmd --help sometimes works. Or online search again.)

About ‘less’

Linux man(ual) pages are not big news actually. What may be more of a news is that the page viewer that is opened by man is actually a text file viewer that is called ‘less’. So, ‘man’ opens up ‘less’ a certain way.

Normally, when the idea is to view any text file, keep it open, and scroll around in it, it’s best to type less filename. A bigger introduction is available at man less, but some of the highlights of ‘less’ are as follows:

• Move around with arrow keys, PgUp, PgDown, Space, Home and End.
• By default, it wraps long lines rather than truncates them, just like all viewers and browsers should do, in my opinion.
• Search with /. Find next with n and find previous with Shift+n.
• Shift+f goes to the end of file and keeps reading it. This is highly useful when piping a file that is being written, to always see its end. For example sudo tcpdump > file | less file and in ‘less’ Shift+f.
• Enable line numbers in the file with the -N option, i.e. less -N file.
• Open the editor with v.
• An overview of the keybinds under h.

Not all these features work when you have ‘man’ open rather than ‘less’, but for example v for editor (which indeed doesn’t work in ‘man’) is a great feature. Normally, one would not want to change the file by mistake, so it makes sense to open it in a viewer like ‘less’, but when the need for editing arises, ‘less’ conveniently redirects there when you press v.

About ‘nano’

The standard editor in Linux is ‘vi’, which happens to be my least favourite editor. The only thing I want to know about it is how to get out of it. For beginners, ‘nano’ is much more convenient, because it has a helpful commands list at the bottom by default.

To enable ‘nano’ over ‘vi’ in the system, put in your .xinitrc or .bashrc (better – in both) the following line:

export EDITOR=/usr/bin/nano

This should be all for most purposes. Usually ‘nano’ comes preinstalled, so nothing to worry about.

Keybinds in ‘nano’

Nano does not use the same keybinds and shortcuts as ‘less’, but this is not a bad thing, because it makes sense to keep the editor function apart from viewer function. On the other hand, ‘nano’ meaningfully uses a bunch of shortcuts similar to bash readline function, such as Ctrl+a “to the beginning of the line” and Ctrl+e “to the end of the line”. Some other shortcuts, somewhat or totally different from bash readline function,* include:

• Ctrl+w to search. Alt+w to repeat last search. Alt+r to find-and-replace.
• Ctrl+k to cut the entire line and store it for pasting.
• Ctrl+u to paste what’s stored.
• Uninterrupted consecutive cuts are all stored-as-one, e.g. three times Ctrl+k cuts three lines below each other and then Ctrl+u restores them all. This enables moving consecutive paragraphs around in the file conveniently. Note however that when the cursor is moved between cuts, the sequence of cuts starts over.
• Ctrl+r to open the system file list, enabling to pick a text file to add into the currently open buffer.
• Ctrl+o to save the file either with the current or a different filename. In this state, Ctrl+t opens the system file list to pick a file to replace (save as).

* See man bash and search for “readline notation”.

Further configuration of ‘nano’

Nano uses the .nanorc file for further configuration. An example of it is located at /etc/nanorc or thereabouts. My ~/.nanorc looks as follows.

  # by default, 'nano' justifies lines to terminal width # which only makes sense when used in 'mutt'; to disable set nowrap set softwrap  # to gain a line for editing, to smoothen scrolling  # and to enable some minimal mousing set morespace set smooth set wordbounds set mouse  # when familiar enough with the keybinds, uncomment # set nohelp 

More advanced hints for ‘nano’ and .nanorc can be found at /etc/nanorc and man nano. And here’s a link to the tutorial that got me started with ‘nano’ a few years ago http://www.tuxradar.com/content/text-editing-nano-made-easy

Rawdog is a console-based RSS feed reader. After installation it doesn’t show up anywhere. It works by typing rawdog in terminal, but there’s some configuration to be done before it does anything useful.

First things after installation

First, copy the config and styles file into the home directory. Issue this in terminal:

cd # to make sure you are in your home directory mkdir .rawdog # to create profile directory for rawdog cp /usr/share/rawdog/config .rawdog/config # copies the default config file into the home directory cp /usr/share/rawdog/styles.css .rawdog/styles.css # copies the styles file into the home directory 

Add feeds

Then add an RSS feed that you want to follow:

rawdog -a https://vivaldi.net/blogs?view=blogger\&layout=listings\&id=443\&format=feed\&type=rss

The URL here is the feed for my Vivaldi blog. The backslashes are escapes needed for console.

Rawdog will report if adding the feed was successful. You can add many feeds of course. The added feeds will appear at the very bottom of the config file located at .rawdog/config.

Sync feeds

To sync the feeds:

rawdog -vWuw

The -W argument is supposed to check the state and state.lock files in the profile directory, i.e. to check the status of previous updates. The -u argument updates the feeds. The -w argument writes the output. The -v argument makes it verbose, so you don’t get bored while waiting the program to finish.

View and configure the output

Rawdog’s output is output.html, a static HTML file. To view the feed, open up .rawdog/output.html in a browser. The style for output.html is in .rawdog/styles.css.

Some other configurable parameters, such as the feed update frequency (rawdog -u doesn’t really update more frequently than the interval specified for the feed in the config file, 3h by default), date formats, etc. can be found in the self-explanatory config file located at .rawdog/config.

A handy oneliner

To keep an eye on the latest posts by my fav feed providers, I have made a command-line alias that stands for

rawdog -vWuw && elinks ~/.rawdog/output.html

Awesome when it works.

Here’s an excellent video about what a tiling window manager is. (I’d prefer to call them tiling desktop as distinguished from windowing desktop, but this is just me.) 

https://youtu.be/sKDQ4rXFCF4 bspwm zsh urxvt tmux vim {Arch Linux}

And for a well-designed installable opsys with Bspwm desktop, you can try http://sourceforge.net/projects/manjarobspwmrespin/files/

W3M is a console webbrowser from Japan. It comes with no upfront help or documentation and its default keybinds are outlandish, so I thought to write up a brief guide to get absolute beginners started.

When installed, the W3M browser can be launched from command line by

w3m $URL

where $URL is a web address or the location of a local HTML file. 

The cursor moves one character at a time with arrow keys, like in an editing environment. W3M is indeed a wonderful tool for web designers. For regular webviewers though, to navigate through the pages quicker, Tab is the key that jumps from a link to next and Ctrl+u does the same backwards. Spacebar scrolls downwards a screen-width and PageUp upwards.

At first it does not function as a proper webbrowser to visit most homey forums and social networks, because cookies are turned off by default. Options are available under the o key, but be ready for a steep learning curve.

Esc does not work as an escape key from fields and situations where the user inadvertently ends up. Ctrl+c does it, mostly. And Shift+b turns back a page (called “buffer” on the options page).

To enter a new web address, press Shift+u. To open all links on the page (a function that I always wanted for Elinks, but is available there only by means of a nasty workaround) press Shift+l.

/ searches forward on the current page. ? searches backward. Shift+q quits without confirmation.

Ins opens up a menu with some of the common commands that the user may need. If you need nothing there, close it with Ctrl+c.

Shift+h opens up a help page with all the rest of the default keybinds. To study and configure the keybinds, download the W3M default keybinds file to .w3m/keymap. Alternatively. you can save a vi-like set of keybinds for W3M to the same location.  

Lua is a scripting language that can be used to extend the functionality of Elinks console browser. Lua can mangle webpages to render them more suitable to Elinks. Lua can also tweak Elinks’ settings in some contexts and launch external programs.

These days, Elinks console browser is commonly pre-compiled for Linux distros with lua support, so the only thing for the user to do is to begin writing extension scripts in lua. But some, such as myself, may be very weak in scripting, and need tutorials and samples.

The best sample is the official hooks.lua file for Elinks. Grab this file, save it to the .elinks directory and enjoy a different console browsing experience on Reddit, Linux Today and Dictionary.com, along with other websites mentioned in the file.

Study the file to devise hacks for the sites that you actually visit with Elinks. I would show what I came up with, but amazingly this blogging environment makes it too difficult to share pure code. <pre> and <code> tags get mangled.

The hooks.lua file testifies that it’s possible to expand Elinks’ keybinds, modify settings and call external programs by means of lua. It even makes YT work in Elinks via youtube-dl! These are all interesting areas to explore.

A text file to write in /usr/sbin/trim

  #!/bin/bash  while read -r i; do echo "$i" | tr '\n' ' '; done

And make executable:

chmod +x /usr/sbin/trim

Requires root rights. Then there should be a new command trim in the system.

Similarly as Thunar allows custom actions, the text editor Medit has the same feature. Here’s a little codebit to trim text with Medit.

Medit’s custom actions are under Preferences/Tools. There you will find a bunch of examples from which to learn, both in regular command line syntax and in more advanced scripting languages. This example is a regular command line.

I often need to trim whitespace and delete all line endings (which are left by pressing Enter) in plain text files. The command line which does it:

sed 's/^[ \t]*//;s/[ \t]*$//' | tr '\n' ' '

Custom actions need a label in Medit’s Tools dialog. In this case “Trim” is fitting. Other applicable settings:

• Requires: Document
• Save: Nothing
• Type: Shell command
• Input: Selected lines
• Output: Insert into the document
• Filter: Default

Thunar has a menu item for custom actions. It’s possible to set regular command line macros there to automatise some common repetitive tasks. For example my common repetitive task is to attach a bunch of files to an email message and I repeat the list of filenames in the email body.

Attaching a bunch of files to an email message in a graphical desktop environment is a simple drag&drop move, but the list of filenames is not that simple. It’s possible to do “copy” on the files and then “paste” in the email message body (or better in a plain text editor) which will result in a list of filenames, but this includes the full harddrive path of the directories.

The problem then is to get rid of the directory paths. It’s not too hard to do Find&Replace (text editors usually have it, more full-featured emailers also), but if the task is highly repetitive (which it is in my work), it gets tedious and an obvious need arises to automatise the task. This is something that users of Thunar can put into custom actions.

There are a few ways in which to automatise the task. Either the list of filenames could be copied to the clipboard, ready for paste, or the list can be opened up in a text editor, ready for review and further editing, if necessary. Let’s first consider copy to clipboard

List of Files onto Clipboard

From command line onto clipboard requires xclip. It needs to be installed, if it’s not already on the system. Then write this custom action:

ls -d %N | xclip -selection c 

Additionally you can set an icon to the custom action, so you will find it easier later in the Thunar menu. This done and applied, when you select multiple files in Thunar (I usually select everything in a folder) and choose the action, the list of filenames will be on clipboard – without directory paths – ready for paste.

List of Files into Editor

Copy to clipboard is a kind of hidden action. If you are not good at remembering or checking what you last copied, then a more visible action may be in order. The list of filenames can be automatically opened up in a text editor, so you see the result of the action.

The problem here is that not every editor allows straightforward piping. The only one I found that does this is Leafpad. I am open to suggestions how other editors accept external input. With Leafpad, it works like this:

ls -d %N | leafpad 

With every other editor, a possible solution is to output the list of filenames as a text file and then open the text file:

ls -d %N > filelist.txt && {editor} filelist.txt

where {editor} is to be replaced with the name of the text editor. This is coarse and unelegant, but the file can be deleted by the end of the operation:

ls -d %N > filelist.txt && {editor} filelist.txt && rm filelist.txt 

This will remove the text file as soon as the editor is closed.

PCLOS Mag has a more extensive tutorial complete with examples of scripts and Zenity prompts http://pclosmag.com/html/Issues/201308/page02.html

Network Manager (or networkmanager) is a comfortable GUI app to switch between internet connections in Linux. The more recent versions of it seem to misbehave more and more, in my experience failing mainly with older Android modems. Here’s a workaround that may help.

The workaround requires dhcp as described at Manjarowiki, but the instructions are a bit different.

1. Determine the devices: ls /sys/class/net This gives you normally three devices on computer to connect to internet: wifi, ethernet, and something called lo.
2. Connect the Android phone, switch it to make modem, and see if it Network Manager fails. If it fails, move on to the next step.
3. Determine the devices again: ls /sys/class/net This time it should list four devices. The fourth is your modem. It’s the one to go for with dhcp.
4. As root, type dhcpcd enp* where enp* should be completed as your fourth device appeared in the previous step.
5. Now there should be internet 🙂

The Manjarowiki instructions also include a step how to make the device permanent in systemd across reboots, but this is not feasible with mobile phone modem, as it sometimes gets differently assigned. The enp* identifier will be different, so it cannot be made permanent.

Otter browser is a project to re-create Opera browser interface, as it stood during Presto era. (Nowadays Opera has moved on to the uninteresting Blink era and lost its unique interface.) 

Otter browser builds interface with Qt5 and renders with Webkit. The development has had a fast pace. The plans look moderately ambitious, i.e. achievable. In weekly 46 release, these Opera-like elements have been re-created:

• Sidebar/Panel (currently featuring only History, Bookmarks, and Downloads)
• Tray icon
• Zoom slider
• Paste-and-go (opens in same tab)
• Pin tabs
• Duplicate tab (called CloneTab)
• Reopen closed tabs
• Website Preferences and Quick Options (F12)
• Save sessions
• Private tabs and private sessions
• Configure search engines
• Set custom fonts, custom colours, and a custom stylesheet
• Configurable keyboard shortcuts in INI file (has its glitches, not all shortcuts can be assigned)
• Configurable menu bar items in JSON file
• Easy switching between translations (you can translate your own language and thus contribute to the project)
• Bookmarks import in Opera format (.adr) and HTML format. Opera bookmarks keywords get imported and assigned correctly
• Keywords can be accessed with QuickBookmarkAccess dialogue just like in Opera with keyboard shortcut Shift+F2
• Secondary address bar with keyboard shortcut F2
• Rocker gestures (mouse buttons left+right to go forward in history, right+left to go back)
• Some incremental Rewind and Fast Forward
• Hint: take a look in about:config

The adress field is still not quite uptodate with suggestions et al., but at this stage I’d call Otter generally usable, particularly because of good cookie support. It’s usable as a general purpose browser, and it’s a joy to follow its development.

Most easily installable packages are available for Arch Linux and Windows. In other distros and opsyses you will have to hunt for Qt dependencies in order to get Otter installed.