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Dev Environment Cheatsheet

Dotfiles - Thoughtbot

I'm using the Thoughtbot Dotfiles with a few local overrides. Thanks to Greg as usual, for turning me on to Thoughtbot. More instructions are on the repo page, as well as the readme for the local overrides.

Installation of Thoughtbot Dotfiles on Linux

Clone the Thoughtbot Dotfiles repo, and then install rcm:

git clone git://github.com/thoughtbot/dotfiles.git ~/dotfiles
sudo add-apt-repository ppa:martin-frost/thoughtbot-rcm
sudo apt-get update
sudo apt-get install rcm
env RCRC=$HOME/dotfiles/rcrc rcup

Now rcup can be run without the environment variable set.

Console/Shell

fzf

  • Trigger fzf and place the result at the command line: C-t
  • Change directory to the result of fzf: M-c (Alt-c)
  • Change directory to the result of fzf: cd **<tab>
  • Search command history with fzf: C-r

Keyboard navigation

Emacs keybindings work, but that's a pain with C-a mapped for tmux. Vim keys work for navigating the list with Ctrl -- C-k to go up, C-j to go down, etc. Select items with enter or tab.

Select multiple entries

fzf --multi

Then use C-k and C-j to navigate the list and tab to toggle selection of each desired item.

Other options

  • fzf --cycle - cycle from the end to the beginning and vice versa
  • fzf --reverse - reverse the list

Use with bat

fzf --preview 'bat --color=always --line-range :50 {}'

Setup with fd and bat

Remember to create symlinks from fd to fdfind and bat to batcat. And set the $FZF_... variables in zshrc.local before sourcing the fzf shell script.

Search example

Show results for src but exclude espnet and __pycache__:

> src !espnet !__pycache__

Completion examples

As outlined in the readme, fzf has a trigger sequence for completions -- **. Change the trigger sequence with $FZF_COMPLETION_TRIGGER.

  • vi **<tab>
  • ssh **<tab>
  • kill <tab> - search for processes by name (no trigger sequence needed)
  • export **<tab>

Command option preview

I haven't found a great way to use this yet, but it's promising.

echo '' | fzf --print-query --preview-window wrap --preview 'cat some_file.json | jq {q}'

Password Manager

KeepassXC on Ubuntu, soon to be on Mac and Windows (when needed)

Regolith - Tiling I3-based Window Manager

Regolith Linux has both a standalone distro and a window manager that can be installed on an existing Ubuntu installation. The latter is what I'm using.

To install on Ubuntu:

sudo add-apt-repository ppa:regolith-linux/release
sudo apt update
sudo apt install regolith-desktop i3xrocks-net-traffic i3xrocks-cpu-usage i3xrocks-time

Then logout or restart. When logging in with gdm, select the gear icon and choose Regolith.

Common Keys:

  • Super is the window key on my laptop
  • Super+Shift+? - open the shortcut/launcher app
  • Super+Enter - terminal
  • Super+Shift+Enter - browser
  • Super+Space - launch an app
  • Super+Shift+q - quit an app
  • Super+c - settings
  • Super+1,2,... - activate the numbered workspace
  • Super+f - toggle fullscreen for the active window
  • Super+arrows - navigate through tiled apps in a workspace
  • Super+Tab - cycle through apps (instead of Alt+Tab)

Ubuntu

Navigation

  • Super+arrows - pin a window to the left or right or maximize it
  • Super+h - hide (minimize) a window

Screenshots

Ubuntu Screenshots and Screencasts

To take a screenshot of a window:

Prt Scrn

To take a screenshot of a selectable region:

Shift + Prt Scrn

Screen recordings

To record the screen I'm using Peek. It has a draggable region and options for saving as a gif, webm, or mp4.

Display info (external screens etc)

List active monitors

xrandr --listactivemonitors

xrandr --listmonitors

Info about all displays

xrandr

Removing PPA Repositories

When getting the annoying "does not have a release file" errors with apt, to remove a repository manually, use add-apt-repository (if ppa-purge is not installed or doesn't work). To remove:

sudo add-apt-repository -r ppa:<name>/<repo>

A troublesome one for me:

sudo add-apt-repository -r ppa:twodopeshaggy/drive

Processing units

When determining how many parallel jobs to pass to make -j, use nproc:

nproc

12

You can use make -j$(nproc) but I'm sparing a few by using make -j8.

Network services

To see info on all running services that are listening on the network:

ss -atpu

DNS

Check whether resolved is running

An active response indicates it's running:

sudo systemctl is-active systemd-resolved.service
active

Flush the resolved DNS cache

sudo systemd-resolve --flush-caches

Check whether network-manager is running

sudo systemctl is-active network-manager
active

Restart network-manager

sudo service network-manager restart

Status for network-manager

sudo service network-manager status

inxi - handy for system info

sudo apt install inxi

Network info:

inxi -n

Other network/wifi tools

nmcli

nmcli show devices

iw dev

iw phy

lshw -C network

Tmux

Prefix

I map my prefix/leader to C-a for easier typing.

Meta

On Mac, in iTerm2, I edit my session to remap the left alt key as Meta (Esc+), more info:

Help, key bindings

<prefix> ?

Resource config files

tmux source ~/.tmux.conf

<prefix> :source ~/.tmux.conf

New named session

To start a new session with <name>:

tmux new -s <name>

:new -s <name>

Rename a session

<prefix> $

Kill a session

tmux kill-session -t <name>

Kill the current session

<prefix> x

Then confirm.

Detach from a session

<prefix> d

List sessions

tmux ls

Switch sessions quickly and visually with:

<prefix> s

Switch to the next and previous sessions

<prefix> (

<prefix> )

Attach to the last session

tmux a

List key bindings

tmux list-keys

or

<prefix> :list-keys

or

<prefix> ?

Selecting text

Hold shift and select text to copy from the terminal.

Scroll through the terminal

Enable scroll/copy mode:

<prefix> [

Then use normal navigation (h/j/k/l) to navigate. Disable with:

q

Copy/Paste in panes with tmux buffers

More here, including info on changing key bindings to match vim.

Default

  1. Enable scroll/copy mode:
<prefix> [
  1. Enter visual select mode:
<space>

  1. Navigate to select a region

  2. Copy the region:

<prefix> w
  1. Paste the copied text:
<prefix> ]

Vim mappings

  1. Enable scroll/copy mode:
<prefix> [
  1. Enter visual select mode:
v

  1. Navigate to select a region

  2. Copy the region:

y
  1. Paste the copied text:
<prefix> P

Paste buffers in Tmux

List paste buffers:

<prefix>:list-buffers

or:

<prefix>=

Show the current buffer:

<prefix>:show-buffer

Show the second buffer:

<prefix>:show-buffer -b 2

Save the current paste buffer to a file named filename.txt:

<prefix>:save-buffer filename.txt

Tmux Plugin Manager

Using tpm

Installation

See the install instructions. Most recently:

  1. Clone the repo to ~/.tmux/plugins/tpm:
git clone https://github.com/tmux-plugins/tpm ~/.tmux/plugins/tpm
  1. Source the tmux config file (this assumes you have the proper entries in the file):
tmux source ~/.tmux.conf

Install plugins and refresh

<prefix> I

tmux-continuum and tmux-resurrect

I'm using tmux-resurrect and tmux-continuum for saving and restoring tmux sessions. Sessions are auto-saved every 15 minutes, but sometimes I manually save them.

Save the current tmux session

<prefix> C-s

Restore the last saved tmux session

<prefix> C-r

Restore alias

To avoid extra steps starting tmux and then restoring, I use an alias to automate it. This is from this issue filed on tmux-resurrect.

alias mux='pgrep -vx tmux > /dev/null && \
           tmux new -d -s delete-me && \
           tmux run-shell $TMUX_DIR/plugins/tmux-resurrect/scripts/restore.sh && \
           tmux kill-session -t delete-me && \
           tmux attach || tmux attach'

Note that this relies on setting $TMUX_DIR, which I do in ~/dotfiles-local/zshrc.local:

TMUX_DIR=$HOME/.tmux

Panes in Tmux

Split pane horizontally

<prefix>"

With mapping:

<prefix>-

Split pane vertically

<prefix>%

With mapping:

<prefix>|

Cycle through pane arrangements

To rearrange panes, cycle through arrangements, use the space/spc key:

<prefix><space>

I hit this on accident periodically, so it's good to know how to correct it.

Navigate panes (with vim mapping)

<prefix>h/j/k/l

Zoom into or out of a pane

<prefix> z

Cycle through zoomed panes

From this question

Add this mapping:

bind -r a select-pane -t .+1 \;  resize-pane -Z

Then cycle through zoomed with <prefix> a, a, a, ...

Convert a pane to a window

<prefix> !

Close the current pane

<prefix> x

Move/swap the current pane

Move the current pane left:

<prefix> {

Move the current pane right:

<prefix> }

Vim

System clipboard access (linux)

Check for the proper compile flags:

vim --version | grep clipboard

You should have +clipboard and +xterm_clipboard. If not then install another vim, I used vim-gnome:

sudo apt install vim-gnome

Now you should have +clipboard and +xterm_clipboard. More info on the Vim Tips Wiki.

set clipboard=unnamed
set clipboard=unnamedplus

Use "+y to yank (copy) to the system clipboard.

System clipboard access (mac)

To copy to the system clipboard (or primary clipboard) on macos:

"+y

or:

"*y

For more info:

:help quoteplus

or:

:help quotestar

Also see accessing the system clipboard.

Edit commands

Edit the previous file: :e# Also: <leader><space>, for me: <space><space>

Leader key

To show your leader key:

:echo mapleader

or

:let mapleader

If it's the space key, it might show up as empty. To see this more explicitly, run:

:nmap showleader :echo('leader key is "<Leader>"')<Esc>| exec 'norm showleader'|
nun showleader

When using space as the leader it prints:

leader key is " "

Go to definition/file/etc

For a keyword under the cursor:

  • gd for the local definition
  • gD for the global definition
  • g* and g# to search forward/backward
  • gf to open the file under the cursor
  • g] to jump to a tag definition
  • :dj /foo to jump to the definition of a class or function matching the pattern foo. See set define for the specification of a definition.

Go to matching brace

To jump between matching braces or supported keyword pairs (Ex: #ifdef/#endif), use the percent key:

%

Go to changes

  • g; - Go to the next older change.
  • g, - Go to the next newer change.

Folding

I mostly only use folding for large data files, like json files.

Enable:

:set foldmethod=syntax

Commands:

  • za toggle a fold
  • zc close a fold
  • zo open a fold

The gutter column

Sometimes it's useful to disable the left gutter column (used by syntax checkers etc) when you want to copy and paste text. How:

:set signcolumn=no

To reenable it:

:set signcolumn=auto

Count words, characters, etc

To count characters, bytes, words, and lines in a selection, select a region and type:

g C-g

This also works on the entire document with no selection active.

Macros

Record a macro to surround a word in double quotes

Yes, this can be done with surround.vim instead.

  1. Press q and a <register> to record into to begin recording, for example: qa
  2. Press viwo<Esc> to go to the beginning of the current word, if not already there. Using wb will work, except where the word is at the end of a file.
  3. Press i to insert and type a quote " (or single quote or other surround character you want to use) and then <Esc> to leave insert mode.
  4. Press e to move to the end of the word.
  5. Press ato append and type a quote " again, then <Esc>.
  6. Press q to write to the register.

To use, move the cursor within a word, and press @<register>, for example: @a. To repeat the last macro, use @@.

List registers

To list registers, including copied text and recorded macros:

:registers

Change inner word

To change the word the cursor is within (vs cw):

ciw

To change the word the cursor is within including the following space:

caw

Changes

List the changes for the current buffer:

:changes

Navigate changes:

  • g; to navigate to the position of the previous change
  • g, to navigate to the position of the next change

Apply an edit to each line in a region

  1. c-v to enter visual block mode
  2. Highlight the region
  3. Make the edit (ex: I foo to prepend " foo" to each line)
  4. esc

Reverse the order of lines

  1. For a region, either specify line numbers or use v to highlight a region
  2. :g/^/m123, where 123 is the destination line number
  3. To explicitly specify line numbers, use :10,20g/^/m9 to reverse lines from 10 to 20.

Ex mode substitutions

Some substitutions for ex mode:

  • % = the current filename 
    :!file %
readme.md: ASCII text, with very long lines

Press ENTER or type command to continue
  • <cword> = sub the current word under the cursor

For more: :help cmdline-special

Searching in Vim

Word boundaries

The word boundary specifiers for vim regex syntax are \< and \>. To search for "the" surrounded by word boundaries:

/\<the\>

Built-in completion

Vim includes several handy completion options which can reduce the need for a plugin. See :h ins-completion for more info. A subset:

  • C-x C-n - complete from keywords in the current file
  • C-x C-i - complete from keywords in the current file and included files
  • C-x C-f - complete from filenames
  • C-x C-l - complete from whole lines in the file
  • C-x C-d - complete from definitions or macros
  • C-x C-] - complete from tags
  • C-x C-u - compete from a user-defined completefunc function (see :h completefunc)
  • C-x C-v - complete from vim command line options

Use C-n and C-p to navigate through the completion list.

Quickfix and location list

The quickfix list and location list are two modes that allow processing lists of data related to the file being edited.

To move between either the quickfix list or location list and the main window, use the same window navigation keys - C-w <hjkl>.

Quickfix

The quickfix list is global to the current session of vim.

  • :copen - Open the quickfix window.
  • :ccl or :cclose - Close the quickfix window.
  • :cnext or :cn - Go to the next item on the list.
  • :cprev or :cp - Go to the previous item on the list.
  • :cfirst - Go to the first item on the list.
  • :clast - Go to the last item on the list.
  • :cc <n> - Go to the nth item on the list.
  • :cdo - run a command for each item in the list
  • :cfdo - run a command for each file in the list
Searching and replacing with quickfix

To search and replace in a project with :cdo:

  1. :grep foo -r **/*.py
  2. :cdo s/foo/bar/ | update - to operate on each match or, to operate on each file: :cfdo %s/foo/bar/g | update
  3. :cfdo bd - to close the opened buffers

The location list

The location list is similar to quickfix but is local to the current buffer.

  • :lopen - Open the location list.
  • :lcl or :lclose - Close the location list.
  • :lnext - Go to the next item on the list.
  • :lprev - Go to the previous item on the list.
  • :lfirst - Go to the first item on the list.
  • :llast - Go to the last item on the list.
  • :ll <n> - Go to the nth item on the list.
  • :ldo - run a command for each item in the list
  • :lfdo - run a command for each file in the list

CtrlP and FZF

To get CtrlP fuzzy file open working, I installed fzf from github:

git clone --depth 1 https://github.com/junegunn/fzf.git ~/.fzf
 ~/.fzf/install

And then edit the dotfiles to move the insertions into the local overrides.

Find files:

:Files [path]

Find Git files:

:GFiles [path]

Find in buffers:

:Buffers

To find text in files - Ripgrep:

:Rg [pattern]

Display full error messages

:messages

Debugging syntax or plugin issues with syntime

  1. Turn syntime on
:syntime on

  1. Cause a redraw or edit (C-l or :e <file>)

  2. Generate a report.

:syntime report

Colortest

:runtime syntax/colortest.vim

Color schemes

Show the current colorscheme

:colorscheme

List all installed colorschemes

:colorscheme <tab>

Set a colorscheme

:colorscheme elflord

Others that are ok:

  • industry
  • koehler
  • pablo
  • ron
  • torte
  • zellner

List loaded scripts/plugins

:scriptnames

To search the loaded scripts

:filter /pattern/ scriptnames

vim-plug

Thoughtbot uses vim-plug as the default vim plugin manager. To install a plugin, edit ~/.vimrc.bundles.local (which should symlink to your local overrides, and add an entry for a plugin like this:

Plug 'maxmellon/vim-jsx-pretty'

Then source .vimrc (or exit and return) and run the install command:

:so ~/.vimrc
:PlugInstall

Sometimes I've found that I have to put the full github path in for some plugins, as can be seen in the bundle file in my local overrides. I also remove some problematic plugins installed by Thoughtbot's defaults.

Uninstalling a plugin

Delete or comment out the Plug entry, then reload .vimrc or restart, and run :PlugClean.

Surround

Some examples:

Key/Command Effect
cs"' Change a surround from "double" to 'single'
cs"[ Change a surround from "double" to [brackets]

YouCompleteMe (ycm)

If receiving the error "The ycmd server SHUT DOWN (restart with :YcmRestartServer)" on launching vim, you may need to launch the ycm server:

cd ~/.vim/bundle/YouCompleteMe
./install.py

Updating ycm

I had to update ycm due to some issues with an update of golang. Steps I took:

cd ~/.vim/bundle/YouCompleteMe/third_party/ycmd
git checkout master
git pull
git submodule update --init --recursive
./build.py --go-completer

Fugitive for Git

fugitive.vim is a git integration for vim.

Some commands:

Key/Command Effect
:Git summary/status
:Git diff or :Gdiff Show diffs
:Git blame or :Gblame Show blame
:Git mergetool & :Git difftool Load diffs into quickfix
:Ggrep and :Glgrep Git grep
:Git add % stage the current file

NERDTree file navigator

Note: I currently have this disabled while trying vim-vinegar.

Key/Command Effect
:NERDTree open NERDTree
o or Enter open a file or expand a directory
C-arrows navigate between NERDTree and an open file
m open the file menu, which allows creating and deleting files and directories
B open bookmarks
:q close NERDTree

I map <leader>ne to open NERDTree:

nmap <leader>ne :NERDTree<cr>

vim-vinegar

vim-vinegar is an alternative file navigation plugin.

Key/Command Effect
- Replace the current buffer with a directory listing, or move up a level if already in vim-vinegar
I Toggle displaying hidden files and netrw header info
y. Yank the absolute path for the file under the cursor
~ Navigate to your home directory
. Start a : command sequence with the path of the file, ex: .grep foo
! Start a shell command with the path of the file, ex: !chmod +x

vim-hug-neovim-rpc pythonx error

Error:

[vim-hug-neovim-rpc] Vim(pythonx):ModuleNotFoundError: No module named 'neovim'

Fix:

  1. Make sure that vim has been compiled with python3 support by running :ver or :echo has('python3')
  2. Run pip3 install pynvim
  3. Run pip3 install neovim

Neovim

NvChad

NvChad is a set of Neovim config that provides a lot of defaults.

Installation

  1. Backup or remove existing nvim config
mv ~/.config/nvim ~/tmp/dot_config_nvim.backup
mv ~/.local/share/nvim ~/tmp/dot_local_share_nvim.backup
  1. Install a nerdfont

Visit nerdfonts.com.

  1. Clone the repo into your config location
git clone git@github.com:NvChad/NvChad.git ~/.config/nvim --depth 1
  1. Run Neovim to see the notes, etc.

Updating

To update, run:

:nvChadUpdate

Commands

The default NvChad leader is space/spc. Pressing the leader and waiting will cause a modal help box to appear.

Key/Command Effect
<leader> + ch Show the NvChad Cheatsheet
<leader> + th Show the theme selector (C-n/C-p for navigation)
C-n Toggle NvimTree
<leader> + ff Find a file
<leader> + fb Find a file in the open buffers
<leader> + / Toggle comment
<leader> + h Horizontal shell
<leader> + v Vertical shell

Treesitter syntax plugins

To check which plugins are installed:

:TSInstallInfo

To install the syntax highlighting plugin for a given language or file:

:TSInstall <type>

Buffers

Key/Command Effect
<tab>, <shift><tab> Cycle through open buffers
<leader> + x Close a buffer

NvimTree

Use C-n to toggle NvimTree for file browsing.

Key/Command Effect
m Toggle marking a file
a Create a file
c Copy a file
p Paste a file
r Rename a file

Dev icons for Nerdtree, etc

To install a patched nerd font on Mac:

brew tap homebrew/cask-fonts
brew install font-jetbrains-mono-nerd-font

Commenting - commentary.vim

Commentary.vim - also works with vim

  • gcc - toggle comment on a line (or a count of lines)
  • gc - toggle comment for a motion (use with visual mode)

Find command - Ripgrep

Use Ripgrep:

rg <pattern>
rg -i <case-insensitive pattern>

Show only filenames of files whose contents match the pattern

rg -l <pattern>

Search only files of a given type with -t (example: python files)

rg -tpy <pattern>

Show the filenames of files whose filenames match the pattern (aliased to rgf)

rg --files | rg <pattern>

Control over ignore/skip of files

By default, ripgrep will ignore binary files, hidden files, and files listed in .gitignore files. This behavior can be changed, from the usage:

    -u, --unrestricted
            Reduce the level of "smart" searching. A single -u won't respect .gitignore
            (etc.) files. Two -u flags will additionally search hidden files and
            directories. Three -u flags will additionally search binary files.

            -uu is roughly equivalent to grep -r and -uuu is roughly equivalent to grep -a -r.

Another way to specifically ignore version control ignore files such as .gitignore files is to use --no-ignore-vcs:

rg --no-ignore-vcs <pattern>

Include all files when searching:

rg -uuu <pattern>

Include all files and search filenames:

rg -uuu --files | rg -uuu <pattern>

An example with a regex and file exclusions

rg \
  --no-ignore-vcs \  # Don't read version control files for ignores
  -g '!*.txt' \      # Exclude files matching *.txt
  -g '!*config*' \   # Exclude files matching *config*
  -li '�foo�' \    # Search for "foo" surrounded by word boundaries, ignoring case
  ./src              # Search in ./src

Git and GitHub

Diffs

Show code diffs with logs

git log -p
git log --graph -p --all

Show diffs of staged files

git diff --cached [filename]

or:

git diff --staged [filename]

Show the diff of the previous commit

git diff HEAD^ HEAD

Show the diff of all changes from when a branch (branch2) branched off from a parent branch (branch1):

git diff branch2...branch1

Create a patch from a diff:

git diff -u --no-prefix > some_patch.diff

Apply the patch:

patch -p0 -i some_patch.diff

Stash

Stash interactively

git stash save -p "some message"

Some options:

y - stash
n - don't stash
q - quit
a - stash this hunk and all later hunks in the file
d - don't stash this hunk or any later hunks in the file

Remotes

Show the remotes for the current project

git remote -v

Switch to the ssh remote url

git remote set-url origin git@github.com:path/to/repo.git

Ex:

git remote set-url origin git@github.com:andypayne/dev_cheatsheet.git

Cloning over HTTPS or SSH

Github now recommmends cloning over HTTPS in their setup guide. No reasons are provided in the guide, but it could be because of the extra key exchange and ssh setup steps.

You can use a credential helper to cache your github credentials when using HTTPS, as described in this article.

Getting the abbreviated commit hash for a commit

All with relative date, name, and subject:

git log --pretty="%h %ar %an %s"

The last two commits with only the abbreviated hashes:

git log -2 --pretty=%h

Reverting the last commit

Get the last two commits:

git log -2 --pretty=%h
78dbbb2
96f95df

Revert to the commit before the last one:

git revert --no-commit 96f95df..HEAD

Combo (untested):

git revert --not-commit `git log -2 --pretty=%h | tail -n 1`..HEAD

Revert and push:

git revert --continue
git push

Forks

Add an upstream repo to a fork:

git remote add upstream git@github.com:user/repo.git

Merge updates from the upstream repo into a fork:

git fetch upstream
git checkout master
git merge upstream/master

Without fast-forwarding:

git merge --no-ff upstream/master

Submodules

Add a submodule to a project:

git submodule add git@github.com:user/repo.git

Update a submodule:

git submodule update --remote

SSH notes

Sharing keys for passwordless login

  1. Generate a key on the local system, if not yet done.

RSA:

ssh-keygen -t rsa

Ed25519:

ssh-keygen -o -a 100 -t ed25519 -f ~/.ssh/id_ed25519 -C "user@example.com"
  1. Copy the public key to the remote system.
ssh-copy-id -i ~/.ssh/id_rsa.pub username@remote.server
  1. Try it.

pkg-config notes

Check for a library/module (OpenCV in this example):

pkg-config --exists --print-errors opencv4

Add /usr/local/lib/pkgconfig as a location (set PKG_CONFIG_PATH in dotfiles):

mkdir /usr/local/lib/pkgconfig
cp opencv4.pc /usr/local/lib/pkgconfig/
export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:$PKG_CONFIG_PATH
pkg-config --exists --print-errors opencv4
echo $?
0

Delete empty directories

Using find to delete empty directories from base/path:

find base/path -type d -empty -delete

Hex dumps

The xxd command can be used to do hex dumps:

echo "foobar" | xxd
00000000: 666f 6f62 6172 0a                        foobar.

Bat (replacement for cat)

bat is a cat alternative with syntax highlighting and git integration.

Install on Ubuntu:

apt install bat

Install on Mac:

brew install bat

Example use with tail -f:

tail -f /var/log/syslog | bat --paging=never -l log
───────┬────────────────────────────────────────────────────────────────────────
       │ STDIN
───────┼────────────────────────────────────────────────────────────────────────
   1   │ Aug 26 09:55:54 host lircd[1288]: lircd-0.10.0[1288]: Error: Cannot glob /sys/class/rc/rc0/input[0-9]*/event[0-9]*
   2   │ Aug 26 09:55:54 host lircd-0.10.0[1288]: Error: Cannot glob /sys/class/rc/rc0/input[0-9]*/event[0-9]*
...

Image, Video, and Audio conversion

Convert from svg to png

With Inkscape:

inkscape -z -w 512 -h 512 image.svg -e image.png

Show media file info

ffprobe video.mp4

Convert a video from mp4 to y4m

This is useful for loading as a media capture file in Chrome.

With ffmpeg:

ffmpeg -i video.mp4 -pix_fmt yuv420p video.y4m

Extract audio from a video

As aac:

ffmpeg -y -i video.mp4 -f aac -vn audio.aac

As wav:

ffmpeg -y -i video.mp4 -f wav -vn audio.wav

cheat.sh

cheat.sh has a nice interface for getting help and examples for common commands. My convenience alias for it is:

cheat() {
  curl cheat.sh/"$@" | bat
}

MacOS

Key repeats on MacOS

To enable key repeats on Mac, set this and then restart:

defaults write -g ApplePressAndHoldEnabled -bool false

Forcing time server sync

To fix a drifting clock on MacOS, force a time server sync:

sudo sntp -sS time.apple.com

PyWhat

PyWhat is a tool for reporting what some unknown data is likely to be. So far I haven't been able to use it for much.

Install and get help:

pip install pywhat && pywhat --help

Example usage:

$ pywhat "123-45-6789"

Possible Identification
┏━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃ Matched Text ┃ Identified as                   ┃ Description                       ┃
┡━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩
│ 123-45-6789  │ American Social Security Number │ An American Identification Number │
└──────────────┴─────────────────────────────────┴───────────────────────────────────┘

FuckIt.py

I haven't tried FuckIt.py yet, but it sounds useful. From the docs: "FuckIt.py uses state-of-the-art technology to make sure your Python code runs whether it has any right to or not. Some code has an error? Fuck it."

One way to use it is by replacing import:

import fuckit
#import some_shitty_module
fuckit('some_shitty_module')
some_shitty_module.some_function()

zoxide

zoxide - on my todo list to try - "zoxide is a blazing fast replacement for your cd command, inspired by z and z.lua. It keeps track of the directories you use most frequently, and uses a ranking algorithm to navigate to the best match."

Also see modern unix.

seq

The seq command will output sequences of numbers.

$ seq 1 10
1
2
3
4
5
6
7
8
9
10

A format string can be passed in:

seq -f "some_file_%02.0f.txt" 100 104
some_file_100.txt
some_file_101.txt
some_file_102.txt
some_file_103.txt
some_file_104.txt

A separator can be specified:

seq -s ":" 4 12
4:5:6:7:8:9:10:11:12:

Zero pad to equal width:

seq -w 0 50000 150000
000000
050000
100000
150000

jot

The jot command will output sequences of random numbers.

jot <reps> <begin> <end>

$ jot 10 1 4
1
1
2
2
2
3
3
3
4
4

Specifying digits of precision:

jot -p 2 5 3 4
3.00
3.25
3.50
3.75
4.00

Specifying a string to repeat:

jot -b hmm 3
hmm
hmm
hmm

Specifying a character to repeat:

jot -c - A F
A
B
C
D
E
F

Generating random numbers in a range:

jot -r 8 10 15
15
11
14
12
14
10
13
14

Specifying a format string:

jot -w "Num: %03d" 3 10
Num: 010
Num: 011
Num: 012

seq and jot can produce the same sequences:

  • seq 5 10 == jot 6 5
  • seq 5 10 == jot - 5 10

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