More Bash Bashing

Advanced Bash Automation for Web Developers

Written by Eva Dee on (about a 4 minute read).

Scripts and Expansions

  • stat [file]

Show file properties such as size, permissions, creation, access dates and more!

  • type [alias]

To quickly check what your alias does.

  • echo $PATH

To see the list of executables.

  • export PATH="$PATH:~/scripts-folder"

To add a folder to the executables (that way you'll be able to run your scripts from anywhere).

  • ln -s ~/scripts-folder/script /usr/local/bin

You can also create a soft link to the usr/local/bin (where your scripts should generally live).

  • cp index.js{,.backup}

This will create a file called index.js.backup with the contents of index.js

  • touch test-{1..10}

Will create 10 test files starting with test-1. Not all commands accept multiple inputs, but touch does.

Bash Navigation

  • !!

Run the last command again.

  • !$

Gives you the last argument of the previous command.

  • ctrl + a: go to the beginning of th line.
  • ctrl + e: go to the end of the line.
  • ctrl + k: to delete the line up to the cursor.
  • ctrl + w: delete the last word.

Curl GitHub

curl -s https://api.github.com/repos/edieblu/includeJS.dev | jq '.stargazers_count'

Get the numbers of stars in a GitHub repo.

jq 

for dep in $(jq -r '.dependencies | keys | .[]' package.json); do
  if ! grep "required\(.*$dep.*)" Rq --exclude-dir="node_modules" ." then
    echo "You can probably remove $dep"
  fi
done

Use jq and grep to find unused dependencies.

  • keys: to get just the keys out of the jq object
  • .[]: array value iterator to get the values in a separate line
  • r: flag in jq means raw text (no quotations)
  • Rq: recursive and quiet

exec

Changes where stdout and stderr go for all commands that come after it.

exec >> log/hooks-out.log 2>&1

Append standard error to the same place and in the same mode than standard output is in.

git diff

if git diff-tree --name-only --no-commit-id ORIG_HEAD HEAD

This will return the differences between the previous and current commits as a bare list of files.

if git diff-tree --name-only --no-commit-id ORIG_HEAD HEAD | grep --quiet 'package.json'; then
 echo "$(date): Running npm install because package.json changed"
 npm install
else
 echo "$(date): No changes in package.json found"
fi

Check if package.json has been changed and run npm install if it did.

  • npm install > /dev/null

If you output to /dev/null the output will be discarded. Note that errors will still be outputed.

Extracting 

case "$1" in
  *.tar|*.tgz) tar -xzvf "$1";;
  *.gz) gunzip -k "$1";;
  *.zip) unzip -v "$1";;
  *)
    echo "Cannot extract $1"
    exit 1
  ;;
esac

A script that extracts a file archive, depending on the file extension.

Random

  • #!/usr/bin/env node

This tells the shell to use the node binary in your environment to execute this file.

  • .plist

A .plist file is an XML-formatted file for macOS.

  • ~/Library/LaunchAgents/

List all applications with job configuration.

Similar notes