5 Essential Ops Hacks: Master sh, History Timestamps, File Transfer, Screen, and Mermaid Diagrams

1. The confusing “sh”

When running install scripts like

curl -sfL https://get.k3s.io | sh

, the

sh

command may point to different shells depending on the distribution.

Debian/Ubuntu derivatives:

sh

is

dash

(lightweight shell).

RHEL/CentOS:

sh

usually links to

bash

(POSIX‑compatible mode).

Alpine Linux:

sh

points to BusyBox’s implementation.

Check the actual link with

ls -l /bin/sh

. If the script relies on Bash‑specific features, invoke

bash

explicitly.

2. Adding timestamps to history

The default

history

command shows no date or time. Add the line

export HISTTIMEFORMAT="%F %T"

to

~/.bashrc

.

%F

prints the full date (YYYY‑MM‑DD) and

%T

prints the time (HH:MM:SS). After reloading,

history

displays entries with timestamps.

3. Copying files across servers without passwords

Two methods:

Use

nc

(netcat): on the source machine run

nc -l 10017 < abc.sh

, on the target run

nc 1.1.1.1 10017 > abc.sh

.

Use Python’s simple HTTP server: on the source run

python -m SimpleHTTPServer 10010

, then download with

wget http://1.1.1.1:10010/abc.sh

or via a browser.

4. Managing multiple terminal windows with Screen

screen

lets you run several terminal sessions inside a single window, detach them, and reattach later. Example to start a session:

screen -S [session_name] ping baidu.com

. List sessions with

screen -ls

.

5. Generating diagrams with Mermaid

Mermaid is a JavaScript‑based tool that creates flowcharts, sequence diagrams, Gantt charts, etc., from Markdown‑style text. It can be combined with DeepSeek to produce full‑lifecycle ops diagrams.