ZSH Field Notes

Misc notes and snippets in a Field Notes style

Links

• ZSH Conditional Expressions
• http://zanshin.net/2013/09/03/how-to-use-homebrew-zsh-instead-of-max-os-x-default/
• Some basic but good generic linux docs
• Parameter Expansion

Path Expansion

#!/usr/bin/zsh
# test script
theVar='/bin/path/file.txt'
echo ${theVar:e}    # txt
echo ${theVar:t}    # file.txt
echo ${theVar:r}    # /bin/path/file
echo ${theVar:h}    # /bin/path
echo ${theVar:h:h}  # /bin
echo ${theVar:t:r}  # file

Substitution

theVar="path/to/a/file.txt"
PTITLE="Hello World"

# Remove leading `path/to/` prefix, if it exists
echo ${theVar#post/}  # a/file.txt

# Replace all occurrences of match (space) with given (underscore)
echo ${PTITLE// /_}   # HELLO_WORLD

# Lowercase/Upercase $PTITLE variable
echo ${(L)PTITLE}     # hello world
echo ${(U)PTITLE}     # HELLO WORLD

Loops

# WHILE - Simple watch
while (sleep 60) do; clear; ./command; done
# FOR - Every file
for f in *.m4v; do mvmedia $f; done
for f in *.{html,sass}; do echo $f; done

# Dump MySQL table 'contents' into development, every M5 /w messages
while (true) do;
  echo "Dumping $(date)...";
  ssh prodsrv "mysqldump database_production contents" | mysql database_development;
  echo "    done";
  sleep 300;
done

# Very simple benchmark
for i in {1..5}; do time echo 'exit' | rails c production; done
for i in {1..5}; do time rake -T > /dev/null; done

# Process a subset of zero padded files, like D02S00.  03-13 in this example:
for s in `seq -f "%02g" 3 13`; do \
  task1.rb "IMG.D02S${s}.mkv" && \
  task2 "IMG.D02S${s}.m4v"; done

Regular Expressions Regex

ITEMS=(
  Desktop
  Pictures
  Backups
)
# Allow specifying items to select as $1, separated by a space (/ /),
if [[ ! -z $1 ]]; then
  # This will become an array
  SPECIFIED_ITEMS=("${(s/ /)1}")
  for i in $SPECIFIED_ITEMS; do
    # This syntax will remove the extension (r), then check the ITEMS
    # collection to get the index ($i), -1 if not found
    if [[ ${${ITEMS[(r)$i]}:--1} == "-1" ]]; then
      echo "*** ERROR: $i is not a valid item! Valid items are: $ITEMS"
      exit 1
    else
      # OK
    fi
  done
  ITEMS=$SPECIFIED_ITEMS
fi

Arrays

# Allow specifying items to override as $1, separated by a space (/ /),
# check to make sure that said items are valid (appear in the ITEMS list).
URLS=(
  Desktop
  Pictures
  Backups
)

# Loop
for f in $URLS; do
  wget $f
done

Hotkeys

• https://coderwall.com/p/a8uxma
• http://www.geekmind.net/2011/01/shortcuts-to-improve-your-bash-zsh.html

History

http://stackoverflow.com/questions/9502274/last-command-in-same-terminal

# Don't share history between sessions
setopt no_share_history

# Share history between sessions
setopt share_history

Passing Arguments to App

Below is a wrapper script that sources [[rbenv]] and passes ALL arguments (correctly) to the ruby script.

#!/bin/zsh
export HOME=/Users/aburns
export PATH=$HOME/.rbenv/bin:$PATH
eval "$(rbenv init -)"
cd $HOME/bin/1.9.3
# echo -E ${(q)@}
ruby ./myIL.rb ${(Q)@}