Speeding up my bashrc
26 July 2025
Recently I’ve been having long startup times when booting up a
terminal instance on my laptop. I traced it to a line in my
.bashrc. I first assumed it was the lines initialising my
mamba environment but I
timed this and it was fast.
I ran time pfetch and noticed it took 3 seconds to run
to completion.
05:27:37 sam@localhost pfetch-caching → time pfetch
_____ ______ sam@localhost.localdomain
/ ____\ / ____ \ os openSUSE Tumbleweed
/ / `/ / \ \ host 2325VZ9 ThinkPad X230
\ \____/ /,____/ / kernel 6.15.4-1-default
\______/ \_____/ uptime 13m
pkgs 5496
memory 4381M / 7643M
real 0m3.177s
user 0m3.076s
sys 0m0.152s
Almost all of this time is due to querying the number of packages on
my system with rpm -qa.
05:39:06 sam@localhost ~ → time rpm -qa | wc -l
5496
real 0m3.249s
user 0m3.159s
sys 0m0.138s
05:39:11 sam@localhost ~ →
I need pfetch in my bashrc (everyone else has
it so I need it too) so removing it isn’t an option.
I decided to cache the result of pfetch with a cron job that runs every minute. I initially defined my job like this
* * * * * pfetch > ~/.pfetch-output
But then I noticed that the .pfetch-output file it
generated was empty. I guessed it was due to it not finding
pfetch so ran which pfetch to find where it
was located and give cron the absolute path. When I did this I was
surprised by receiving “mail” in /var/mail/sam
05:25:33 sam@localhost pfetch-caching → which pfetch
/home/sam/.local/bin/pfetch
You have mail in /var/mail/samI didn’t actually know I could receive mail like this
05:25:35 sam@localhost pfetch-caching → cat /var/mail/sam
From sam@localhost Sat Jul 26 05:25:01 2025
Return-Path: <sam@localhost>
X-Original-To: sam
Delivered-To: sam@localhost
Received: by localhost (Postfix, from userid 1000)
id 37EC92AF2CC; Sat, 26 Jul 2025 05:25:01 +0100 (BST)
From: "(Cron Daemon)" <sam@localhost>
To: sam@localhost
Subject: Cron <sam@localhost> pfetch > .pfetch-output
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Auto-Submitted: auto-generated
Precedence: bulk
X-Cron-Env: <LANG=en_GB.UTF-8>
X-Cron-Env: <SHELL=/bin/sh>
X-Cron-Env: <HOME=/home/sam>
X-Cron-Env: <PATH=/usr/bin:/bin:/usr/sbin:/sbin>
X-Cron-Env: <LOGNAME=sam>
X-Cron-Env: <USER=sam>
Message-Id: <20250726042501.37EC92AF2CC@localhost>
Date: Sat, 26 Jul 2025 05:25:01 +0100 (BST)
/bin/sh: line 1: pfetch: command not found
Which is what I expected the issue to be and replacing
pfetch with /home/sam/.local/bin/pfetch
produces the right output. I replaced the pfetch call in my
bashrc with cat .pfetch-output and my bashrc takes less
than a year to run which is quite nice.
Actually, since the only issue with pfetch was finding the number of packages on my system, I decided to cache the package list to a file and modify pfetch so that it read from this file.
05:51:54 sam@localhost pfetch-caching → crontab -l
* * * * * rpm -qa > .rpm-qa-output
05:51:56 sam@localhost pfetch-caching →
This has the added bonus that when pfetch runs I have an
up-to-date memory usage. As an aside, I learned how to do line-profiling
of bash scripts which I find kinda funny and feels pretty extra and
unecessary.
To be honest, I find this entire fiasco a bit funny.