Difference between revisions of "Chromium/Tips and tricks"

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(Run in a Sandbox: the seccomp sandbox is on by default)
(1024-bit DH is disabled by deault, too)
 
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[[Category:Web Browser]]
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[[Category:Web browser]]
[[zh-CN:Chromium Tips and Tweaks]]
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[[ja:Chromium 設定]]
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[[zh-cn:Chromium/Tips and tricks]]
 
{{Related articles start}}
 
{{Related articles start}}
 
{{Related|Chromium}}
 
{{Related|Chromium}}
{{Related|Firefox Tweaks}}
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{{Related|Firefox tweaks}}
 
{{Related articles end}}
 
{{Related articles end}}
  
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An automatically updated, complete listing of Chromium switches is available [http://peter.sh/experiments/chromium-command-line-switches/ here].
 
An automatically updated, complete listing of Chromium switches is available [http://peter.sh/experiments/chromium-command-line-switches/ here].
  
=== Broken icons in Download Tab ===
+
=== Broken icons in Download tab ===
If Chromium shows icon placeholders (icons representing broken documents) instead of appropriate icons in its download tab, the likely cause is that the {{Pkg|gnome-icon-theme}} package is not installed.
+
If Chromium shows icon placeholders (icons representing broken documents) instead of appropriate icons in its Download tab, the likely cause is that the {{Pkg|gnome-icon-theme}} package is not installed.
  
 
=== Chromium overrides/overwrites Preferences file ===
 
=== Chromium overrides/overwrites Preferences file ===
Line 26: Line 27:
 
  $ chromium --disable-sync-preferences
 
  $ chromium --disable-sync-preferences
  
If Chromium is started in the background when you login in to your desktop environment, make sure the command your desktop environment uses is
+
If Chromium is started in the background when you login in to your desktop environment, make sure the command your desktop environment uses is:
 
  $ chromium --disable-sync-preferences --no-startup-window
 
  $ chromium --disable-sync-preferences --no-startup-window
  
=== Scroll speed of mouse wheel ===
+
=== Search engines ===
As of 22 Feb 2013, upstream has [https://code.google.com/p/chromium/issues/detail?id=154776 removed] the {{ic|--scroll-pixels}} flag. The {{AUR|chromium-scroll-pixels}} package can be installed from the [[AUR]], which contains a patch to enable the {{ic|--scroll-pixels}} flag.
+
Make sites like [https://wiki.archlinux.org wiki.archlinux.org] and [https://en.wikipedia.org wikipedia.org] easily searchable by first executing a search on those pages, then going to ''Settings > Search'' and click the ''Manage search engines..'' button. From there, "Edit" the Wikipedia entry and change its keyword to '''w''' (or some other shortcut you prefer). Now searching Wikipedia for "Arch Linux" from the address bar is done simply by entering "'''w arch linux'''".
 
+
{{Tip|Due to long compilation times, the original [https://wiki.archlinux.org/index.php/User:Graysky uploader] provides pre-compiled packages in his unofficial repo, [[repo-ck]].}}
+
 
+
Example usage:
+
 
+
$ chromium --scroll-pixels=320
+
 
+
=== Search Engines ===
+
Make sites like wiki.archlinux.org and wikipedia.org easily searchable by first executing a search on those pages, then going to ''Settings > Search'' and click the ''Manage search engines..'' button. From there, "Edit" the Wikipedia entry and change its keyword to "w" (or some other shortcut you prefer). Now searching Wikipedia for "Arch Linux" from the address bar is done simply by entering "w arch linux".
+
  
 
{{Note| Google search is used automatically when typing something into the URL bar. A hard-coded keyword trigger is also available using the '''?''' prefix.}}
 
{{Note| Google search is used automatically when typing something into the URL bar. A hard-coded keyword trigger is also available using the '''?''' prefix.}}
Line 50: Line 42:
 
  $ chromium --disk-cache-dir=/tmp/cache
 
  $ chromium --disk-cache-dir=/tmp/cache
  
Cache should be considered temporary and will '''not''' be saved after a reboot or hard lock.
+
Cache should be considered temporary and will '''not''' be saved after a reboot or hard lock. Alternatively, use:
  
Alternative way, in {{ic|/etc/fstab}}:
+
{{hc|/etc/fstab|2=
tmpfs /home/<USER>/.cache tmpfs noatime,nodev,nosuid,size=400M 0 0
+
tmpfs /home/''username''/.cache tmpfs noatime,nodev,nosuid,size=400M 0 0
 +
}}
  
{{Note|Adjust the size as needed and be careful. If the size is too large and you are using a sync daemon such as [[psd]] on a conventional HDD, it will likely result in very slow start-up times of your graphical system due to long sync back times of the daemon. }}
+
{{Warning|Adjust the size as needed and be careful. If the size is too large and you are using a sync daemon such as [[psd]] on a conventional HDD, it will likely result in very slow start-up times of your graphical system due to long sync back times of the daemon. }}
  
 
==== Profile in tmpfs ====
 
==== Profile in tmpfs ====
Line 69: Line 62:
 
  $ chromium --user-data-dir=<PATH TO A PROFILE>
 
  $ chromium --user-data-dir=<PATH TO A PROFILE>
  
{{Note|It won't work if you specify a link or even a symlink to your regular chromium profile (typically {{ic|~/.config/chromium/Default}}). If you want to use the same profile as your current one for this new instance, first copy the folder {{ic|~/.config/chromium/Default}} to a directory of your choice, keeping the same {{ic|Default}} name, and launch the browser using the following command by specifying the parent folder of the {{ic|Default}} folder you have just copied.
+
{{Note|It will not work if you specify a link or even a symlink to your regular Chromium profile (typically {{ic|~/.config/chromium/Default}}). If you want to use the same profile as your current one for this new instance, first copy the folder {{ic|~/.config/chromium/Default}} to a directory of your choice, keeping the same {{ic|Default}} name, and launch the browser using the following command by specifying the parent folder of the {{ic|Default}} folder you have just copied.
e.g. if you copied the Default folder to ~/Downloads/
+
For example, if you copied the Default folder to {{ic|~/Downloads}}:
  
{{bc|1=$ chromium --user-data-dir=~/Downloads}}
+
{{bc|1=$ chromium --user-data-dir=~/Downloads}}
 
}}
 
}}
  
 
===Directly open *.torrent files and magnet links with a torrent client===
 
===Directly open *.torrent files and magnet links with a torrent client===
By default, Chromium downloads {{ic|*.torrent}} files directly and you need to click the notification from the bottom left corner of the screen in order for the file to be opened with your default torrent client. This can be avoided with the following method:
+
 
 +
By default, Chromium downloads {{ic|*.torrent}} files directly and you need to click the notification from the bottom-left corner of the screen in order for the file to be opened with your default torrent client. This can be avoided with the following method:
  
 
* Download a {{ic|*.torrent}} file.
 
* Download a {{ic|*.torrent}} file.
* Right click the notification displayed at the bottom left corner of the screen.
+
* Right-click the notification displayed at the bottom-left corner of the screen.
* Check the "Always Open Files of This Type" checkbox.
+
* Check the "''Always Open Files of This Type''" checkbox.
  
For torrent magnet links to open with Deluge automatically when they are clicked, run the following commands:
+
See [[xdg-open]] to change the default assocation.
  
{{Note|If you would like to use Transmission instead of Deluge, you can use {{ic|transmission-gtk.desktop}} here instead.}}
+
=== Touch Scrolling on touchscreen devices ===
 +
Chrome and Chromium do not support touchscreen by default. There are a couple settings you can change in the "Flags" portion of Chrome to potentially make it work for your device. This has been tested in {{Pkg|chromium}} from the [[official repositories]] and {{AUR|google-chrome}} from the [[AUR]].
  
$ gvfs-mime --set x-scheme-handler/magnet deluge.desktop
+
* Browse to '''chrome://flags''' and set everything to default
$ xdg-mime default deluge.desktop x-scheme-handler/magnet
+
* Switch "''Enable Touch events''" to "''Enabled''" ('''chrome://flags/#touch-events''')
 +
* Restart Chrome and touch scrolling should work. If it does not, it is worth trying the other modes that are available.
 +
* You may need to specify which touch device to use. Find your touchscreen device with {{ic| xinput list}} then launch Chromium with the {{ic|1=--touch-devices='''x'''}} parameter, where "'''x'''" is the id of your device. {{Note|If the device is designated as a slave pointer, using this may not work, use the master pointer's ID instead.}}
  
==Profile Maintenance ==
+
=== Disable system tray icon ===
Chromium uses [[Sqlite]] databases to manage history and the like.  Sqlite databases become fragmented over time and empty spaces appear all around. But, since there are no managing processes checking and optimizing the database, these factors eventually result in a performance hit. A good way to improve startup and some other bookmarks and history related tasks is to defragment and trim unused space from these databases.
+
  
{{AUR|profile-cleaner}} and {{AUR|browser-vacuum}} in the [[AUR]] do just this.
+
Open the URL {{ic|chrome://flags}} in the browser. Disable this flag:
  
== Security ==
+
* {{ic|device-discovery-notifications}}
=== Disable insecure RC4 cipher  ===
+
  
Since a while RC4 is declared as insecure, but the cipher is still in Chrome present. You should disable the cipher in Chrome. This can be done by starting chrome from the command line with following option:
+
Click the restart button at the bottom of the page.
  
/usr/bin/chromium --cipher-suite-blacklist=0x0001,0x0002,0x0004,0x0005,0x0017,0x0018,0xc002,0xc007,0xc00c,0xc011,0xc016,0xff80,0xff81,0xff82,0xff83
+
=== Reduce memory usage ===
  
You can check for that on https://cc.dcsec.uni-hannover.de/ for the supported list if ciphers. Make sure to test it before and after you make the change.  
+
By default, Chromium uses a separate OS process for each ''instance'' of a visited web site. [https://www.chromium.org/developers/design-documents/process-models#Supported_Models] However, you can specify command-line switches when starting Chromium to modify this behaviour.
  
To make the change persistent, you can modify the {{ic|/etc/chromium/default}} and add the line above. To check, open the website mentioned before. A alternative is to grep inside of your process list for the keyword cipher. 
+
For example, to share one process for all instances of a website:
  
'''External Information''':
+
$ chromium --process-per-site
  
There is no cleaner way to disable. Also the [https://code.google.com/p/chromium/codesearch#chromium/usr/include/nss/sslproto.h source-code] only show the right hexadecimal value for the single cipher.
+
To use a single process model:
basic information with recommendation to disable RC4 on [https://en.wikipedia.org/wiki/RC4 wikipedia RC4]
+
  
[http://blog.pregos.info/2013/11/13/howto-disable-weak-rc4-cipher-in-firefox-chromium-google-chrome-internet-explorer/comment-page-1/#comment-141763 German Blog] showing to disable RC4 in common browsers.
+
$ chromium --single-process
 +
 
 +
{{Warning|While the single-process model is the default in [[Firefox]] [https://wiki.mozilla.org/Electrolysis] and other browsers, it may contain bugs not present in other models. [https://www.chromium.org/developers/design-documents/process-models#TOC-Single-process]}}
 +
 
 +
In addition, you can suspend or store inactive Tabs with extensions such as [https://chrome.google.com/webstore/detail/tab-suspender/fiabciakcmgepblmdkmemdbbkilneeeh?hl=en Tab Suspender] and [https://chrome.google.com/webstore/detail/onetab/chphlpgkkbolifaimnlloiipkdnihall?hl=en OneTab].
  
 
=== User Agent===
 
=== User Agent===
By default Chromium already sends an excessively detailed User Agent, as is viewable via the EFF's [https://panopticlick.eff.org/ Panopticlick] test. That alone makes each browser readily identifiable with high accuracy — and is further exacerbated by the use of non-stable versions, ones not recently provided by Google's release channels, ones customized e.g. by a distribution (such as the AUR's {{AUR|chromium-browser-ppa}}), etc.
 
  
However, this User Agent can be arbitrarily modified at the start of Chromium's base instance via its {{Ic|<nowiki>--user-agent="[string]"</nowiki>}} parameter.
+
The User Agent can be arbitrarily modified at the start of Chromium's base instance via its {{Ic|<nowiki>--user-agent="[string]"</nowiki>}} parameter.
  
For the same User Agent as the stable Chrome release for Linux i686 (at the time of writing the most popular Linux edition of Chrome) one would use:
+
For the same User Agent as the stable Chrome release for Linux i686 (at the time of writing, the most popular Linux edition of Chrome) one would use:
 
  --user-agent="Mozilla/5.0 (X11; Linux i686) AppleWebKit/535.2 (KHTML, like Gecko) Chrome/20.0.1132.47 Safari/536.11"
 
  --user-agent="Mozilla/5.0 (X11; Linux i686) AppleWebKit/535.2 (KHTML, like Gecko) Chrome/20.0.1132.47 Safari/536.11"
  
 
An official, automatically updated listing of Chromium releases which also shows the included WebKit version is available as the [https://omahaproxy.appspot.com/ OmahaProxy Viewer].
 
An official, automatically updated listing of Chromium releases which also shows the included WebKit version is available as the [https://omahaproxy.appspot.com/ OmahaProxy Viewer].
  
=== Making it all persistent ===
+
==Profile maintenance ==
You can export your flags from {{ic|~/.profile}}:
+
Chromium uses [[SQLite]] databases to manage history and the likeSqlite databases become fragmented over time and empty spaces appear all around. But, since there are no managing processes checking and optimizing the database, these factors eventually result in a performance hit. A good way to improve startup and some other bookmarks- and history-related tasks is to defragment and trim unused space from these databases.
  export CHROMIUM_USER_FLAGS="--disk-cache-dir=/tmp --disk-cache-size=50000000"
+
  
Or add them to {{ic|/etc/chromium/default}}:
+
{{AUR|profile-cleaner}} and {{AUR|browser-vacuum}} in the [[AUR]] do just this.
{{bc|<nowiki>
+
# Default settings for chromium. This file is sourced by /usr/bin/chromium
+
#
+
# Options to pass to chromium
+
CHROMIUM_FLAGS="--scroll-pixels=200"</nowiki>
+
}}
+
  
Chromium will prefer the user defined flags in {{ic|CHROMIUM_USER_FLAGS}} to those defined in {{ic|/etc/chromium/default}}.
+
== Security ==
 +
=== WebRTC ===
 +
WebRTC is a communication protocol that relies on JavaScript that can leak one's actual IP address from behind a VPN. While software like NoScript prevents this, it's probably a good idea to block this protocol directly as well, just to be safe.  An [https://code.google.com/p/chromium/issues/detail?id=457492 option to disable it] is available via an [https://chrome.google.com/webstore/detail/webrtc-network-limiter/npeicpdbkakmehahjeeohfdhnlpdklia extension].
 +
 
 +
One can test this via [https://www.privacytools.io/webrtc.html this page].
  
If you want to use {{ic|CHROMIUM_USER_FLAGS}} and Pepperflash, you should add Chromium Pepperflash arguments to your {{ic|~/.profile}} file.  
+
=== SSL certificates ===
  export CHROMIUM_USER_FLAGS="--ppapi-flash-path=/usr/lib/PepperFlash/libpepflashplayer.so --ppapi-flash-version=11.7.700.141"
+
Chromium does not have an SSL certificate manager.  It relies on the NSS Shared DB {{ic|~/.pki.nssdb}}.  In order to add SSL certificates to the database, users will have to use the shell.  
  
=== SSL Certificates ===
+
==== Adding CAcert certificates for self-signed certificates ====
Unfortunately, Chromium doesn't have a SSL certificate manager.  It relies on the NSS Shared DB {{ic|~/.pki.nssdb}}.  In order to add SSL certificates to the database, users will have to use the shell.
+
Grab the CAcerts and create an {{ic|nssdb}}, if one does not already existTo do this, first install the {{Pkg|nss}} package, then complete these steps:
  
==== Adding CAcert Certificates for Self-Signed Certificates ====
+
  $ mkdir -p $HOME/.pki/nssdb
Grab the CAcerts and create a nssdb if one does not already exist. To do this, first install the {{Pkg|nss}} package, then complete these steps:
+
$ cd $HOME/.pki/nssdb
{{bc|<nowiki>[[ ! -e $HOME/.pki/nssdb ]] && mkdir -p $HOME/.pki/nssdb && cd $HOME/.pki/nssdb && certutil -N -d sql:.</nowiki>}}
+
$ certutil -N -d sql:.
{{Note|Users will need to create a password for the database should it not exist.}}
+
  
{{bc|<nowiki>curl -k -o "cacert-root.crt" "http://www.cacert.org/certs/root.crt"
+
$ curl -k -o "cacert-root.crt" "http://www.cacert.org/certs/root.crt"
curl -k -o "cacert-class3.crt" "http://www.cacert.org/certs/class3.crt"
+
$ curl -k -o "cacert-class3.crt" "http://www.cacert.org/certs/class3.crt"
certutil -d sql:$HOME/.pki/nssdb -A -t TC -n "CAcert.org" -i cacert-root.crt  
+
$ certutil -d sql:$HOME/.pki/nssdb -A -t TC -n "CAcert.org" -i cacert-root.crt  
certutil -d sql:$HOME/.pki/nssdb -A -t TC -n "CAcert.org Class 3" -i cacert-class3.crt
+
$ certutil -d sql:$HOME/.pki/nssdb -A -t TC -n "CAcert.org Class 3" -i cacert-class3.crt
</nowiki>}}
+
  
{{Note|Users will need to create a password for the database should it not exist.}}
+
{{Note|Users will need to create a password for the database, if it does not exist.}}
  
 
Now users may manually import a self-signed certificate.
 
Now users may manually import a self-signed certificate.
  
==== Example 1: Using a Shell Script Isolate the Certificate from TomatoUSB ====
+
==== Example 1: Using a shell script to isolate the certificate from TomatoUSB ====
Below is a simple script that will extract and add a certificate to the user's nssdb:
+
Below is a simple script that will extract and add a certificate to the user's {{ic|nssdb}}:
  
 
  #!/bin/sh
 
  #!/bin/sh
Line 177: Line 169:
 
*http://blog.avirtualhome.com/adding-ssl-certificates-to-google-chrome-linux-ubuntu
 
*http://blog.avirtualhome.com/adding-ssl-certificates-to-google-chrome-linux-ubuntu
  
==== Example 2: Using Firefox to Isolate the Certificate from TomatoUSB ====
+
==== Example 2: Using Firefox to isolate the certificate from TomatoUSB ====
The {{Pkg|firefox}} browser can used to save the certificate to a file for manunal import into the DB.
+
The {{Pkg|firefox}} browser can be used to save the certificate to a file for manual import into the database.
  
 
Using firefox:
 
Using firefox:
 
#Browse to the target URL.
 
#Browse to the target URL.
#Upon seeing the "This Connection is Untrusted" warning screen, click I understand the Risks>Add Exception...
+
#Upon seeing the "This Connection is Untrusted" warning screen, click: ''I understand the Risks > Add Exception...''
#Click View>Details>Export and save the certificate to a temporary location ({{ic|/tmp/easy.pem}} in this example).
+
#Click: ''View > Details > Export'' and save the certificate to a temporary location ({{ic|/tmp/easy.pem}} in this example).
  
 
Now import the certificate for use in Chromium:
 
Now import the certificate for use in Chromium:
  certutil -d sql:$HOME/.pki/nssdb -A -t TC -n "easy" -i /tmp/easy.pem
+
  $ certutil -d sql:$HOME/.pki/nssdb -A -t TC -n "easy" -i /tmp/easy.pem
  
{{Note|Adjust the name to match that of the certificate. In the example above, "easy" is the name on the certificate.}}
+
{{Note|Adjust the name to match that of the certificate. In the example above, "easy" is the name of the certificate.}}
  
 
Reference:
 
Reference:
 
*http://sahissam.blogspot.com/2012/06/new-ssl-certificates-for-tomatousb-and.html
 
*http://sahissam.blogspot.com/2012/06/new-ssl-certificates-for-tomatousb-and.html
 +
 +
== Making flags persistent ==
 +
{{Note|Starting with {{ic|chromium 42.0.2311.90-1}} only per-user flags are supported.}}
 +
 +
You can put your flags in a {{ic|chromium-flags.conf}} file under {{ic|$HOME/.config/}} (or under {{ic|$XDG_CONFIG_HOME}} if you have configured that environment variable).
 +
 +
No special syntax is used; flags are defined as if they were written in a terminal.
 +
 +
* The arguments are split on whitespace and shell quoting rules apply, but no further parsing is performed.
 +
* In case of improper quoting anywhere in the file, a fatal error is raised.
 +
* Flags can be placed in separate lines for readability, but this is not required.
 +
* Lines starting with a hash symbol (#) are skipped.
 +
 +
Below is an example {{ic|chromium-flags.conf}} file that defines the flags {{ic|--start-maximized --incognito}}:
 +
 +
# This line will be ignored.
 +
--start-maximized
 +
--incognito
 +
 +
{{Tip|If you have Pepper Flash installed, the launcher will automatically pass the correct flags to Chromium so you do not need to define any {{ic|--ppapi-flash-*}} flags.}}
 +
 +
{{Note|The {{ic|chromium-flags.conf}} file is specific to Arch Linux and is supported via a custom launcher script that was added in {{ic|chromium 42.0.2311.90-1}}.}}
  
 
== See also ==
 
== See also ==

Latest revision as of 14:21, 20 April 2016

Related articles

Browsing experience

chrome://xxx

A number of tweaks can be accessed via typing chrome://xxx in the URL field. A complete list is available by typing chrome://chrome-urls into the URL field. Some of note are listed below:

  • chrome://flags - access experimental features such as WebGL and rendering webpages with GPU, etc.
  • chrome://plugins - view, enable and disable the currently used Chromium plugins.
  • chrome://gpu - status of different GPU options.
  • chrome://sandbox - indicate sandbox status.
  • chrome://version - display version and switches used to invoke the active /usr/bin/chromium.

An automatically updated, complete listing of Chromium switches is available here.

Broken icons in Download tab

If Chromium shows icon placeholders (icons representing broken documents) instead of appropriate icons in its Download tab, the likely cause is that the gnome-icon-theme package is not installed.

Chromium overrides/overwrites Preferences file

If you enabled syncing with a Google Account, then Chromium will override any direct edits to the Preferences file found under $HOME/.config/chromium/Default/Preferences. To work around this, start Chromium with the --disable-sync-preferences switch:

$ chromium --disable-sync-preferences

If Chromium is started in the background when you login in to your desktop environment, make sure the command your desktop environment uses is:

$ chromium --disable-sync-preferences --no-startup-window

Search engines

Make sites like wiki.archlinux.org and wikipedia.org easily searchable by first executing a search on those pages, then going to Settings > Search and click the Manage search engines.. button. From there, "Edit" the Wikipedia entry and change its keyword to w (or some other shortcut you prefer). Now searching Wikipedia for "Arch Linux" from the address bar is done simply by entering "w arch linux".

Note: Google search is used automatically when typing something into the URL bar. A hard-coded keyword trigger is also available using the ? prefix.

Tmpfs

Cache in tmpfs

Note: Chromium actually keeps its cache directory separate from its browser profile directory.

To limit Chromium from writing its cache to a physical disk, one can define an alternative location via the --disk-cache-dir=/foo/bar flag:

$ chromium --disk-cache-dir=/tmp/cache

Cache should be considered temporary and will not be saved after a reboot or hard lock. Alternatively, use:

/etc/fstab
tmpfs	/home/username/.cache	tmpfs	noatime,nodev,nosuid,size=400M	0	0
Warning: Adjust the size as needed and be careful. If the size is too large and you are using a sync daemon such as psd on a conventional HDD, it will likely result in very slow start-up times of your graphical system due to long sync back times of the daemon.

Profile in tmpfs

Relocate the browser profile to a tmpfs filesystem, including /tmp, or /dev/shm for improvements in application response as the entire profile is now stored in RAM.

Use an active profile management script for maximal reliability and ease of use.

profile-sync-daemonAUR is such a script and is directly available from the AUR. It symlinks and syncs the browser profile directories to RAM. Refer to the Profile-sync-daemon wiki article for additional information on it.

Launch a new browser instance

When you launch the browser, it first checks if another instance using the same profile is already running. If there is one, the new window is associated with the old instance. To prevent this, you can specifically ask the browser to run with a different profile.

$ chromium --user-data-dir=<PATH TO A PROFILE>
Note: It will not work if you specify a link or even a symlink to your regular Chromium profile (typically ~/.config/chromium/Default). If you want to use the same profile as your current one for this new instance, first copy the folder ~/.config/chromium/Default to a directory of your choice, keeping the same Default name, and launch the browser using the following command by specifying the parent folder of the Default folder you have just copied.

For example, if you copied the Default folder to ~/Downloads:

$ chromium --user-data-dir=~/Downloads

Directly open *.torrent files and magnet links with a torrent client

By default, Chromium downloads *.torrent files directly and you need to click the notification from the bottom-left corner of the screen in order for the file to be opened with your default torrent client. This can be avoided with the following method:

  • Download a *.torrent file.
  • Right-click the notification displayed at the bottom-left corner of the screen.
  • Check the "Always Open Files of This Type" checkbox.

See xdg-open to change the default assocation.

Touch Scrolling on touchscreen devices

Chrome and Chromium do not support touchscreen by default. There are a couple settings you can change in the "Flags" portion of Chrome to potentially make it work for your device. This has been tested in chromium from the official repositories and google-chromeAUR from the AUR.

  • Browse to chrome://flags and set everything to default
  • Switch "Enable Touch events" to "Enabled" (chrome://flags/#touch-events)
  • Restart Chrome and touch scrolling should work. If it does not, it is worth trying the other modes that are available.
  • You may need to specify which touch device to use. Find your touchscreen device with xinput list then launch Chromium with the --touch-devices=x parameter, where "x" is the id of your device.
    Note: If the device is designated as a slave pointer, using this may not work, use the master pointer's ID instead.

Disable system tray icon

Open the URL chrome://flags in the browser. Disable this flag:

  • device-discovery-notifications

Click the restart button at the bottom of the page.

Reduce memory usage

By default, Chromium uses a separate OS process for each instance of a visited web site. [1] However, you can specify command-line switches when starting Chromium to modify this behaviour.

For example, to share one process for all instances of a website:

$ chromium --process-per-site

To use a single process model:

$ chromium --single-process
Warning: While the single-process model is the default in Firefox [2] and other browsers, it may contain bugs not present in other models. [3]

In addition, you can suspend or store inactive Tabs with extensions such as Tab Suspender and OneTab.

User Agent

The User Agent can be arbitrarily modified at the start of Chromium's base instance via its --user-agent="[string]" parameter.

For the same User Agent as the stable Chrome release for Linux i686 (at the time of writing, the most popular Linux edition of Chrome) one would use:

--user-agent="Mozilla/5.0 (X11; Linux i686) AppleWebKit/535.2 (KHTML, like Gecko) Chrome/20.0.1132.47 Safari/536.11"

An official, automatically updated listing of Chromium releases which also shows the included WebKit version is available as the OmahaProxy Viewer.

Profile maintenance

Chromium uses SQLite databases to manage history and the like. Sqlite databases become fragmented over time and empty spaces appear all around. But, since there are no managing processes checking and optimizing the database, these factors eventually result in a performance hit. A good way to improve startup and some other bookmarks- and history-related tasks is to defragment and trim unused space from these databases.

profile-cleanerAUR and browser-vacuumAUR in the AUR do just this.

Security

WebRTC

WebRTC is a communication protocol that relies on JavaScript that can leak one's actual IP address from behind a VPN. While software like NoScript prevents this, it's probably a good idea to block this protocol directly as well, just to be safe. An option to disable it is available via an extension.

One can test this via this page.

SSL certificates

Chromium does not have an SSL certificate manager. It relies on the NSS Shared DB ~/.pki.nssdb. In order to add SSL certificates to the database, users will have to use the shell.

Adding CAcert certificates for self-signed certificates

Grab the CAcerts and create an nssdb, if one does not already exist. To do this, first install the nss package, then complete these steps:

$ mkdir -p $HOME/.pki/nssdb
$ cd $HOME/.pki/nssdb
$ certutil -N -d sql:.
$ curl -k -o "cacert-root.crt" "http://www.cacert.org/certs/root.crt"
$ curl -k -o "cacert-class3.crt" "http://www.cacert.org/certs/class3.crt"
$ certutil -d sql:$HOME/.pki/nssdb -A -t TC -n "CAcert.org" -i cacert-root.crt 
$ certutil -d sql:$HOME/.pki/nssdb -A -t TC -n "CAcert.org Class 3" -i cacert-class3.crt
Note: Users will need to create a password for the database, if it does not exist.

Now users may manually import a self-signed certificate.

Example 1: Using a shell script to isolate the certificate from TomatoUSB

Below is a simple script that will extract and add a certificate to the user's nssdb:

#!/bin/sh
#
# usage:  import-cert.sh remote.host.name [port]
#
REMHOST=$1
REMPORT=${2:-443}
exec 6>&1
exec > $REMHOST
echo | openssl s_client -connect ${REMHOST}:${REMPORT} 2>&1 |sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p'
certutil -d sql:$HOME/.pki/nssdb -A -t TC -n "$REMHOST" -i $REMHOST 
exec 1>&6 6>&-

Syntax is advertised in the commented lines.

Reference:

Example 2: Using Firefox to isolate the certificate from TomatoUSB

The firefox browser can be used to save the certificate to a file for manual import into the database.

Using firefox:

  1. Browse to the target URL.
  2. Upon seeing the "This Connection is Untrusted" warning screen, click: I understand the Risks > Add Exception...
  3. Click: View > Details > Export and save the certificate to a temporary location (/tmp/easy.pem in this example).

Now import the certificate for use in Chromium:

$ certutil -d sql:$HOME/.pki/nssdb -A -t TC -n "easy" -i /tmp/easy.pem
Note: Adjust the name to match that of the certificate. In the example above, "easy" is the name of the certificate.

Reference:

Making flags persistent

Note: Starting with chromium 42.0.2311.90-1 only per-user flags are supported.

You can put your flags in a chromium-flags.conf file under $HOME/.config/ (or under $XDG_CONFIG_HOME if you have configured that environment variable).

No special syntax is used; flags are defined as if they were written in a terminal.

  • The arguments are split on whitespace and shell quoting rules apply, but no further parsing is performed.
  • In case of improper quoting anywhere in the file, a fatal error is raised.
  • Flags can be placed in separate lines for readability, but this is not required.
  • Lines starting with a hash symbol (#) are skipped.

Below is an example chromium-flags.conf file that defines the flags --start-maximized --incognito:

# This line will be ignored.
--start-maximized
--incognito
Tip: If you have Pepper Flash installed, the launcher will automatically pass the correct flags to Chromium so you do not need to define any --ppapi-flash-* flags.
Note: The chromium-flags.conf file is specific to Arch Linux and is supported via a custom launcher script that was added in chromium 42.0.2311.90-1.

See also