Invocations and commands
General, not macOS-specific or
Linux-specific.
I try to cover mostly standard commands here but sometimes the features of the invoking shell are also important.
You could optimise that also, e.g. by switching from
bash
to fish
or
PowerShell.
Modernization
Why do we stick to the classic 80s Unix tools? mhoye recommends updating standard CLI utilities, as does Benjamin Pollack. Edited highlights from those post dominate this page.
Improvements on “classic” tools and utilities:
ripgrep, a line-oriented search tool that recursively searches the current directory for a regex pattern described as a better grep.
fd, a “A simple, fast and user-friendly alternative to 'find'”
The moreutils collection. Editied highlights:
- chronic: runs a command quietly unless it fails
- combine: combine the lines in two files using boolean operations
- errno: look up errno names and descriptions
- ifdata: get network interface info without parsing ifconfig output
- ifne: run a program if the standard input is not empty
- isutf8: check if a file or standard input is utf-8
- lckdo: execute a program with a lock held
- mispipe: pipe two commands, returning the exit status of the first
- parallel: run multiple jobs at once
- pee: tee standard input to pipes
- sponge: soak up standard input and write to a file (allows us to pipe to and from the same file)
- ts: timestamp standard input
- vidir: edit a directory in your text editor
- vipe: insert a text editor into a pipe
- zrun: automatically uncompress arguments to command
atool, a set of scripts that wrap common compressed-file-format handlers.
bat, a “better cat”.
There’s also zoxide: an interesting update to, of all things, cd!
Broot: better navigation of directory trees.
mcfly: McFly replaces your default
ctrl-r
shell history search with an intelligent search engine that takes into account your working directory and the context of recently executed commands. McFly’s suggestions are prioritized in real time with a small neural network.
There are many more under text data processing.
Resource monitoring
htop, “a cross-platform interactive process viewer.” An htop-like utility called bottom also got some votes.
As an aside, about htop: one commenter noted that they run HTOP on a non-interactive TTY, something like control-alt-F11; so do I, and it’s great, but you must not do this on sec-critical systems. You can kill processes through htop, and that gives you a choice of signals to issue, and on most machines running systemd
systemd init
responds to SIGTRMIN+1 by dropping back into rescue mode, and that’s a backstage pass to a root shell. I have used this to recover a personal device from an interrupted upgrade that broke PAM. You must never do this on a machine that matters.ncdu, friend of htop and a nice disk usage display for the terminal.
duf a better df
dust: “du on steroids.”
duc, also a nice drive-use visualizer.
Tree: show you the tree structure of directories, a bit like microdosing on Midnight Commander from back in the day.
Not really a new thing but a quality of life improvement: the “ducks” alias., “ducks: linux command for the 10 largest files in current directory”
Nice prompts
Who owns this PID?
ps -o user -p $PID
WTF ^M
?
Return produces ^M
instead of a newline?
Try:
stty sane^J
or possibly
stty icrn^J
For other miscellaneous screen garbage, maybe reset will help?
reset
It is more complicated if I made a mess in tmux.
As far as I am concerned this is all dark magic. If this nonsense wastes 2 hours of my life in total it will not justify the rather lengthier process of getting a better mental model of how terminals work.
File system watching
In Watch That Filesystem,
Al Williams discusses how to trigger things based on filesystem events via
inotifywait
and incron
.
Thanks Yohans Bastian for pointing out this handy trick to find the PID of the process using the inotify watchers.
find /proc/*/fd \
-lname anon_inode:inotify \
-printf '%hinfo/%f\n' 2>/dev/null \
| xargs grep -c '^inotify' \
| sort -n -t: -k2 -r
Cross platform filewatcher: emcrisostomo/fswatch:
A cross-platform file change monitor with multiple backends: Apple OS X File System Events, *BSD kqueue, Solaris/Illumos File Events Notification, Linux inotify, Microsoft Windows and a stat()-based backend.
rebuild on change
entr watches for changed files and recompiles your whatsit when it gets edited. This is incredibly useful for automating life.
Which file is crashing/hanging $PID
?
lsof -r -p $PID | grep /path/to/file
Vars, expansions, file names, white space hell
See bash
or fish
depending on choice of shell.
Or avoid both by using some other utility, such as…
rename
rename
is a script
that makes renaming work how I imagine it should,
avoiding the mysterious punctuation stew at least somewhat.
rename -s html txt *.html
NB depending on distro you may get some other systutil rename which is much less powerful than the one I linked to, albeit still often powerful enough.
Text processing
Trailing whitespace
A shell script to remove trailing whitespace from a file -
put this in trimspace.sh
:
#!/bin/bash
# macOS version
sed -i '' -e’s/[[:space:]]*$//' "$1"
#!/bin/bash
# GNU version
sed -i -e’s/[ \t]*$//' "$1"
Then you can trim trailing whitespace from your… whatever… by putting this line in there:
find . -type f -print0 | xargs -0 -I {} trimspace.sh \{\}
Data wrangling
See text data processing.
Incoming
rsync files in random order
based of Ole Tange’s tor version
Remotely
find . -maxdepth 4 -depth -type d | shuf | rsync --delete -zHax --inplace --rsync-path='mkdir -p {} && rsync' ~/{}/ remote.host:/some/dir/{}/
Presumably this works locally:
for file in (find . -maxdepth 4 -depth -type d | shuf)
mkdir -p "$file" && rsync --delete -Hax --inplace - ./{}/ /some/dir/{}/
end
Download from command line without getting owned
curl --tlsv1.2 --proto=https --location \
--remote-name-all --remote-header-name
Find common diacritics in filenames
Caught in unicode crossfire? Try
find . -iname "*[üñàáèéöäçã]*"
Which process is bound to port $PORT
?
lsof -nP -i4TCP:$PORT | grep LISTEN
Sync only if drive present
test -d /Volumes/syncdrive/ && rsync --delete -avz \
192.168.0.1:/path/to/stuff/ /Volumes/syncdrive/
Unzip zips into subdir using fish
for foo in *.zip
unzip $foo -d (basename $foo .zip)
end
Set operations
comm
.
Meta command lines
Command lines to command your command lines.
I suppose if I were a good person I’d check if any of the above commands are novel and submit them to tldr
or version my .cheats
folder in a
dotfile repo,
or mention them in commandlinefu
but I’m now exhausted and just want to go home.
Fig
Fig is a command line autocompleter and syncer and secret manager which focuses on enabling teams with sahred shortcuts and utilities.
Explainshell
Explainshell dissects a shell command and shows you the documentation for each part of it. Good for instilling this knowledge in your brain.
tldr
tldr
:
New to the command-line world? Or just a little rusty? Or perhaps you can’t always remember the arguments to
lsof
, ortar
?
…And the manual for your typical command is utterly incomprehensible, so remembering is obviously preferable to trying to decipher it.
First
## install
npm install -g tldr
# or
brew install tldr
# invoke
tldr tar
Alternative implementation:
## install
brew install tealdeer
# invoke is still
tldr tar
cheat
…allows you to create and view interactive cheatsheets on the command-line. It was designed to help remind *nix system administrators of options for commands that they use frequently, but not frequently enough to remember.
## install
pip install cheat
# or
brew install cheat
# invoke
cheat tar
how do i
Are you a hack programmer? Do you find yourself constantly Googling for how to do basic programming tasks?
Suppose you want to know how to format a date in bash. Why open your browser and read through blogs (risking major distraction) when you can simply stay in the console and ask
howdoi
pip install howdoi
howdoi tar
Seems to search the internet for you, and not be command-line specific, which is broader in scope than some of the other entrants here, but also noisier.
commandlinefu
commandlinefu has an awful command-line interface, but the website is so good that it makes the grade.
bash hackers wiki
bash hackers wiki: avoid its the paradigmatically awful bash
manual
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