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CLI - Tips & Tricks

PATH

Print all entries in $PATH line by line

# For bash, zsh
echo $PATH | sed 's/:/\n/g'

# For fish
echo $PATH | sed 's//\n/g'

# Output
/home/admin/.local/bin # The shell checks this directory first
/home/admin/bin
/usr/local/bin
/usr/local/sbin
/usr/bin
/usr/sbin

Command history

What is command history

(Almost) everything you type to the terminal is saved.

Where is the command history

The command history is stored at $HISTFILE, which by default:

For bash, it's ~/.bash_history,
For zsh, it's ~/..zsh_history,
For fish, its's ~/.local/share/fish/fish_history

How to use command history

Access last command:
- Press Arrow Up
- Press Arrow Up more for last of last command
- ...
Search for a command is the command history: Ctrl + R

For a default bash, zsh prompt, it looks like this
```
(reverse-i-search)`’:
```
Use atuin¹ for a magical 🪄 shell history, which:
- records additional context for your commands
- synchronizes your history between machines/shells

Command completion

Use Warp² terminal
Use fish³ shell
Use argc-completions⁴

How to know how to use a command?

Use --help, -h, help flag/option/sub-command
- Some commands support --help
```
uname --help
```
```
uname -h # Does't work
```
- Some commands support -h
```
dig -h
```
```
dig --help # Doesn't work
```
- Some commands support both --help, -h and even have a sub-command named help
```
go help
```
```
go -h
```
```
go --help
```
- Some commands don't support --help or -h, and don't have a help sub-command either, e.g. ssh, ssh-keygen
```
$ ssh -h
unknown option -- h
```
```
$ ssh --help
unknown option -- -
```
```
$ ssh help
ssh: Could not resolve hostname help: Name or service not known
```
Access the command's manual pages
```
man uname
```
Use tldr⁵, cheat⁶
```
tldr uname
```
```
cheat uname
```