I got this output from ps aux|grep firefox command:

$ ps aux|grep firefox
auraham   5443 17.3 11.0 2600628 426484 ?      Sl   18:10   0:54 /usr/lib/firefox/firefox
auraham   5496 24.0 17.9 2558108 691700 ?      Sl   18:10   1:15 /usr/lib/firefox/firefox -contentproc -childID 1 -isForBrowser -intPrefs 5:50|6:-1|18:0|28:1000|33:20|34:10|43:128|44:10000|49:0|51:400|52:1|53:0|54:0|59:0|60:120|61:120|91:2|92:1|106:5000|117:0|119:0|130:10000|155:24|156:32768|158:0|159:0|167:5|171:1048576|172:100|173:5000|175:600|176:4|177:1|186:2|200:60000| -boolPrefs 1:0|2:0|4:0|26:1|27:1|30:0|35:1|36:0|37:0|38:0|41:1|42:1|45:0|46:0|47:0|48:0|50:0|55:1|56:1|57:0|58:1|62:1|63:1|64:0|65:1|66:1|67:0|68:1|71:0|72:0|75:1|76:1|80:1|81:1|82:1|83:0|85:0|86:0|87:1|88:0|93:1|94:0|100:0|105:0|108:1|109:0|111:1|112:1|114:1|118:0|120:0|122:0|124:1|125:1|131:0|132:0|133:1|135:0|146:0|153:0|154:0|157:1|160:0|162:1|164:1|165:0|170:0|174:1|179:0|180:0|181:0|182:1|183:0|184:0|185:1|188:1|192:0|193:0|194:1|195:1|196:0|197:1|198:1|199:1|201:0|202:0|204:0|212:1|213:1|214:0|215:0|216:0| -stringPrefs 3:7;release|134:3;1.0|151:332;  ¼½¾ǃː??։֊׃״؉؊٪۔܁܂܃܄ᅟᅠ᜵           ???‐’․‧??????? ‹›⁁⁄⁒ ⅓⅔⅕⅖⅗⅘⅙⅚?⅜⅝⅞⅟∕∶⎮╱⧶⧸⫻⫽⿰⿱⿲⿳⿴⿵⿶⿷⿸⿹⿺⿻ 。〔〕〳゠ㅤ㈝㈞㎮㎯㏆㏟꞉︔︕︿﹝﹞?./。ᅠ???�|152:8;moderate| -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appdir /usr/lib/firefox/browser 5443 true tab
auraham   5694  0.0  0.0  15444  1092 pts/2    S+   18:15   0:00 grep --color=auto firefox

According to this blog, this error occurs after firefox crashes. However, every time I run Firefox again, that large line of arguments appears too.

I already try these things:

  • Run Firefox with addons disabled
  • Reinstall Firefox (sudo apt-get purge firefox; sudo apt-get install firefox)

However, it did not work.

Is it possible to remove such a line of arguments?

  • The page you linked to is a forum thread which appears to suggest this is normal behaviour for Firefox. Is this causing you a problem? – Xyon Sep 20 '17 at 14:19
  • here is a oneliner to get usable pgrep firefox output: pgrep -fai firefox/firefox | awk '/contentproc/{for(i=6;i<=21;i++){$i="#"};print $0;next}{print $0}' – lesmana Apr 11 '18 at 18:38

Probably not removable, but that will appear only when browsing web pages.

What is that line of argument

When running Firefox 54 or newer release, the Multiprocess Firefox (a.k.a. Electrolysis or e10s) is now enabled by default for all users. The latter link has explanation for the matter on MozillaWiki.

Electrolysis functionality hosts, renders, or executes web related content in background child processes which communicate with the "parent" Firefox browser via various ipdl protocols.

So the line of argument -contentproc -childID 1 -isForBrowser [...] appears in process list because Firefox is running with multiprocess enabled by default.

The cryptic part of argument  ¼½¾ǃː̷̸։֊׃״؉؊٪۔܁܂܃܄ᅟᅠ᜵ [...] seems to correspond to the blacklisted characters by Mozilla, as per network.IDN.blacklist_chars documentation at MozillaZine, which was hinted by this partial answer by TT Farreo at Stack Overflow.

The blacklisted characters are also found in the configuration of Firefox itself, which can be accessed at about:config from the address bar. See the following screenshot as proof.

In about:config, search 'network.IDN'

How to check multiprocess

Open Firefox, then type 'about:support' in address bar and press Enter key. User will be presented with Troubleshooting Information page. Look under Application Basics, scroll down further to see Multiprocess Windows option.

If multiprocess is disabled in Firefox for known reason:

Multiprocess Windows 0/1 (Disabled by add-ons)

If multiprocess is enabled in Firefox:

Multiprocess Windows 1/1 (Enabled by default)

Web Content Processes 0/1

The "Web Content Processes" may have different values based on the performance settings in Firefox. The value '0/1' is shown because in Preferences > General, under Performance section, "Content process limit" option has been set to '1'. If set to '4', then the value is '0/4'.

Whether shown or not

From my observation, I have identified the following cases:

  1. With multiprocess disabled: No argument throughout the session
  2. With multiprocess enabled: Has argument (when active)

Note that "when active" means a process with the line of argument -contentproc -childID 1 -isForBrowser ... will appear when Firefox is used for browsing web pages. The process will appear throughout the session.

Say if only 'about:' URL pages are opened in Firefox, then the process won't appear at all even multiprocess is enabled. See following screenshot as proof.

When Firefox multiprocess is shown and not shown

TL;DR: The process with line of argument is not rare, but is normal to see when running Firefox 54 or newer for all users. That is because multiprocess is now enabled by default.

  • 1
    I am discussing this in another post - my progress so far is here - and requested an FF architect on Reddit from here to comment as well (no response just yet.) I've been poking at it again, it's really starting to get to me (and I found a mistake in my answer, still figuring it out.) Lots of other people have been asking too, but all I can find is that it's expected & benign. – John P Jan 23 '18 at 6:56

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