dev-notes.md

Development and Mac Notes

Collection of useful tools, aliases, shortcuts, etc. which come in handy.

Words file

/usr/share/dict/words

Special Characters

On macOS, the following allow for special characters (when the ABC - Extended keyboard is set):

Accent	Sample	Keystrokes
Breve	Ŏ, ŏ	Option+b, X
Circumflex	Ŵ, ŵ	Option+6, X
Hacheck	Č, č	Option+v, X
Macron	Ō, ō	Option+a, X
Ring	Å, å	Option+k, A
Strikethrough Bar	ł, ɨ	Option+l, X
Subscript Dot	ṣ, ḍ	Option+x, X
Superscript Dot	ṡ, ḟ	Option+w, X

Command Line

Generate a Dot Graph Graphviz

dot -Tpng file.dot -o ruby-deps.png
dot -Tsvg file.dot -o ruby-deps.svg

Copy Data with Only ssh

# Copy Data by Bouncing through intermediary:
< foo.tgz ssh <intermediary-ip> "ssh <destination-box> 'cat - > foo.tgz'"

# Copy data to a machine.
< file-name ssh dest "cat - > file-name"

# Copy data from a machine
> file-name ssh remote-host "cat - < file-name"

Loop over Files with Spaces in Name

OIFS="$IFS"
IFS=$'\n'
for f in `ls *.html`; do
  echo "$f"
done
IFS="$OIFS"

Generate a UUID

uuidgen

Replace Value in JSON

new_id=$(uuidgen) && jq ".request" file.json | jq ".user.ids[0].value = \"${new_id}\"" | pbcopy

Display Multiple Fields

jq '.selected_diagnostics[] | .date, .name' source.json

Conditionally Show Selected Fields

jq '.selected_diagnostics[] | select ( .name | contains("MP")) | .date, .name' source.json

Join Every Line but the Seventh:

perl -pi -e 's/\n/\t/ if $.%7' copied-table.txt

Check if Command Available in Shell Script

if ! [ -x "$(command -v git)" ]; then
  echo 'Error: git is not installed.' >&2
  exit 1
fi

Remove by iNode

ls -i
find . -inum <inode> -exec rm -i {} \;

Force Reinstall of All brew Libraries

brew reinstall `brew list`

Copy File to S3 Bucket

aws s3 cp --sse AES256 <file> s3://destination/path/

Get Your External IP Address

curl ipinfo.io

Get JVM Options

java -XX:+UnlockDiagnosticVMOptions -XX:+PrintFlagsFinal -version

List Unique Lines without Sorting

awk '! seen[$0]++'

Remove Lines from file2 that Are Found in file1

grep -F -v -f file1 file2 > remaining

To Redirect where slime Is Pointing

^-c v

To Sort a File by Line Length, Longest First

cat testfile | awk '{ print length, $0 }' | sort -nr | cut -d" " -f2-

Largest Directories Relative to .

du -hs */ | sort -hr | head

Find git Commits Involving File, Even if File Doesn't Exist Anymore

git log --full-history -- app/assets/images/3.gif

Search Old Changeset for String

git log -Swhat_i_am_looking_for

Audit git for Authors

for f in $(find lib/finance_api -type f); do
  echo $f
  git annotate -w -M -C -C --line-porcelain "$f" | grep -I '^author ' | sort -f | uniq -ic | sort -n --reverse
done

In-Place sed on OSX

sed -i '' 's/before/after' <file>

Hex to Decimal

echo $((0x077C))
# And the other way:
printf '%x\n' 432

PostgreSQL (and psql in Particular)

Copy data to a CSV file.

\copy (SELECT x FROM y WHERE z=1) TO '/tmp/xyz.csv' DELIMITER ',' CSV HEADER;

Turn off Paging

\pset pager off

Get Settings from Query

SHOW ALL;

vim

Copy to Clipboard

:w !pbcopy
" or use "+

See What the Current Mappings Are:

:map
:nmap " normal mode
:vmap " visual mode
:imap " insert mode
:help index " to see all the build-in commands

Copy Contents of File into Current Position

:read <file-name>

Address Spelling Highlights

" Move to next highlight
]s
" Move to previous highlight
[s
" Add current word to dictionary
zg
" Remove current work from dictionary
zw

Redraw the Screen if Things Have Gone Odd

:redraw!

Text Alignment with

:right
:center
:left

Saving and Restoring Sessions

" May want to add 'Session.vim' to .gitignore
:mksession!
$ vim -S

Search for non-ASCII Characters

/[^\x00-\x7F]

Increment with Every Matching Line of Visual Selection

g ctrl-a/ctrl-x

Column-wise Deletion

d<c-v>2j

Delete until Matching Line

d/regex/-1

Why Is Start-up Slow?

vim --startuptime /dev/stdout slow_to_open_file.ex +q | less

Search for merge conflicts

/[<=>][<=>][<=>][<=>][<=>][<=>][<=>]

Ruby

Read in Hash-syntax Map from File

data = JSON.parse(File.read('/path/to/file-name').gsub('=>', ':'))

Use Rails to Access DB

RAILS_ENV=production bundle exec rails dbconsole -p

Create pg_dump Command from Rails Config

awk '/host/ {host=$2}; /password/ {pass=$2}; /database/ {dbname=$2}; /port/ {port=$2}; /username/ {username=$2}; END {printf("\npassword is: %s\n\ndump command is:\n pg_dump --format=c --host=%s --port=%s --dbname=%s --username=%s > /tmp/%s-$(date +%%F).dump\n", pass, host, port, dbname, username, dbname)}' config/local_database.yml

ClojureScript

Use a RegEx as a Filter

(extend-type js/RegExp
 IFn
 (-invoke
  ([this a]
   (re-find this a))))

JavaScript

List Methods on Specific Object

getMethods = (obj) => Object.getOwnPropertyNames(obj).filter(item => typeof obj[item] === 'function')

const getMethods = (obj) => {
  let properties = new Set()
  let currentObj = obj
  do {
    Object.getOwnPropertyNames(currentObj).map(item => properties.add(item))
  } while ((currentObj = Object.getPrototypeOf(currentObj)))
  return [...properties.keys()].filter(item => typeof obj[item] === 'function')
}

Use json-server to Treat JSON File as DB

npx json-server --watch db.json --port 3001

Node

npm list -g --depth 0 to list all global packages.

npm update to update all packages to the latest (allowed). npm outdated to identify which libraries have newer versions.

npm install -g npm-check-updates will then allow for ... ncu -u which will update all versions globally.