Bash-completion is very slow on MSYS2 (original) (raw)

Bash-completion is very slow on MSYS2 when the current user is a domain user. This describes the cause and the solutions.

Cause

Expansion of ~* is very slow when you use a domain user. For example:

$ time echo ~*
~*

real    0m23.151s
user    0m0.000s
sys     0m0.000s

When the tab key is pressed, bash-completion tries to evaluate ~*. That's why bash-completion is slow.

Solution 1: Disable ~* in bash_completion

~* is used inside /usr/share/bash-completion/bash_completion. Disabling it can solve the problem.

--- /usr/share/bash-completion/bash_completion.org +++ /usr/share/bash-completion/bash_completion @@ -542,9 +542,9 @@ elif [[ $1 == '* ]]; then # Leave out first character printf -v 22 %s "2{1:1}"

• elif [[ $1 == ~* ]]; then

•    # avoid escaping first ~

•    printf -v <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mn>2</mn><mtext> </mtext></mrow><annotation encoding="application/x-tex">2 ~%q &quot;</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.6444em;"></span><span class="mord">2</span><span class="mspace nobreak"> </span></span></span></span>{1:1}"

• #elif [[ $1 == ~* ]]; then

• # avoid escaping first ~

• printf -v 2 2 ~%q "2 {1:1}"

  else printf -v 22 %q "21" fi

Solution 2: Disable db in /etc/nsswitch.conf

MSYS2 obtains the user information from the system database (in Windows) by default, but it is very slow when the current user is a domain user. Disabling it and make MSYS2 to obtain the user information from files solves the problem.

First you need to create /etc/passwd and /etc/group with the information of the local users (-l) and the current (domain) user (-c).

$ mkpasswd -l -c > /etc/passwd $ mkgroup -l -c > /etc/group

Then you need to modify /etc/nsswitch.conf to disable db from group andpasswd.

--- /etc/nsswitch.conf.org +++ /etc/nsswitch.conf @@ -1,7 +1,7 @@

Begin /etc/nsswitch.conf

-passwd: files db -group: files db +passwd: files #db +group: files #db

db_enum: cache builtin

If you don't update /etc/passwd and /etc/group properly, bash prompt might show your account as Unknown+User.

See also:

• man 5 nsswitch.conf on Linux
• msys2/MSYS2-packages#138 (comment)