Something weird appears when I click on Tow icon to open browser: an icon with binary numbers, a lock and an X appears. the icon's name is "sedCh0n6k". What is it? I am using Ubuntu.


This is a temporary file left behind by the sed command-line utility.

sed describes itself as "a stream editor", saying "A stream editor is used to perform basic text transformations on an input stream (a file or input from a pipeline)". It's often used in shell scripts for searching and replacing text and similar operations on text files.

sed is used in a few places in the start-tor-browser shell script which sets up the environment for Tor Browser to run properly before launching firefox.

Normally sed should be cleaning this up after it has finished processing the file by renaming it to the original file.

$ echo 'foo' > test # create a simple text file
$ strace -e open,rename sed -i 's/foo/bar/' test # trace the calls to 'open' and 'rename' that sed makes
[ ... unimportant syscalls ... ]
open("test", O_RDONLY)                  = 3
open("./sed2WewTJ", O_RDWR|O_CREAT|O_EXCL, 0600) = 4
rename("./sed2WewTJ", "test")           = 0
+++ exited with 0 +++

sed created a new file called sed2WewTJ (the prefix being sed and the suffix 2WewTJ being random) then once it's done operating on the file it renames the file to test to replace the original file with the newly edited file, to avoid directly operating on the original file.

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