Bash script can tell its location

You can get the path of the directory in which a bash script is located FROM that bash script.


Read more about this problem on stackoverflow.

Replace line break with comma in bash

Get links from a page with bash

Get anchor elements from a webpage can be done with

curl URL 2>&1 | grep -o -E 'href="([^"#]+)"' | cut -d'"' -f2


where you replace URL with your choice, just like here:
curl http://cookpad.com 2>&1 | grep -o -E 'href="([^"#]+)"' | cut -d'"' -f2


Switching back to the previous application with AppleScript

If you want to simulate cmd + tab with AppleScript, here it is

tell application "System Events"
  tell process "finder"
    activate
    keystroke tab using {command down}
  end tell
end tell

You can use the same thing in bash

echo 'tell application "System Events"
  tell process "finder"
    activate
    keystroke tab using {command down}
  end tell
end tell' | osascript

Image width/height with Imagemagick in Command line

Imagemagick comes handy when you need information from an image.

# width
w=`identify -format "%w" image.png`

# height
h=`identify -format "%h" image.png`

More information on Imagemagick's identify.

bash history

Bash history preserved in ~/.bash_history there are a few ways to search it.
history | grep

history | grep git

the output would be like that
475 git checkout -f
479 gitx
481 git co sp/sprint1
487 git co master
488 git branch -D sp/sprint1
489 git br
491 git co sp/sprint1
496 git diff | gitx
502 git st
510 history | grep git


the followings will reference to line '502 git st'
> !502

# counting back from the last one
> !-1

# same as !-1
> !!

using the last event starting with 'git'
> !git



Or press Ctrl-R, and as you start typing the search goes back in reverse order to the first command that matches the letters you’ve typed.

Once you’ve found the command you have several options:

- Run it verbatim – just press Enter
- Cycle through other commands that match the letters you’ve typed – press Ctrl-R successively
- Quit the search and back to the command line empty-handed – press Ctrl-G


if you're using the history a lot you may want to add these line to your bash init file (~/.bash_profile)


# remove duplicates from the history
export HISTCONTROL=erasedups

# increases the history size
export HISTSIZE=10000

# ensures that when you exit a shell, the history from the session is appended to bash_history
shopt -s histappend


I copy and pasted from the following articles
working-with-history-in-bash, bash-history-reverse-intelligent-search, man history

i like Bash a lot.

Get HTTP status code with curl in bash


curl --write-out %{http_code} --silent --output /dev/null URL

and then wrapping it into a function

getHTTPCode () {
    echo $(curl --write-out %{http_code} --silent --output /dev/null $1)
}


response=$(getHTTPCode URL)
echo $response


Turning off case-sensitive tab completion in bash

/etc/inputrc deals with the mapping of the keyboard for certain situations.

Adding

set completion-ignore-case on

to the file turns off case-sensitivity in tab completion.


echo set completion-ignore-case on | sudo tee -a /etc/inputrc


Installing NodeJS from source on Snow Leopard


git clone https://github.com/joyent/node.git
cd node

mkdir ~/local
./configure --prefix=$HOME/local/node
make
make install
export PATH=$HOME/local/node/bin:$PATH


Now if you open a new terminal window

node --version

you should see the new version number.

Get page response time with bash


(time curl URL --head) 2>&1 | grep real | cut -c 6-

for instance

(time curl http://google.com --head) 2>&1 | grep real | cut -c 6-

the response is something like this
0m0.072s

Editing files in the user's path

I have lots of scripts in my path but the actual location differs.

If i have to edit them i often do
vim `which FILE_NAME`

for example
vim `which port_utility`


The which utility takes a command name and searches the path for each executable file that would be run had this commands actually been invoke.

Reload the browser when files change on OSX

Web front-end development often looks like this, you change the code, which can be HTML, CSS, JavaScript, Ruby whatever and then you head over to the browser and reload it to see the changes.

This is not a big deal, but what if the browser could automatically does the reload.

My solution has three parts.

1. You can detect file change with Kicker.


2. Set the focus to the browser and reload it with AppleScript.


3. Set the focus back to your texteditor.

Let's combine these

kicker -e "osascript reload-browser.applescript;focus-textmate.applescript" FOLDER_TO_WATCH

In my case this looks like this

kicker -e "osascript ~/workspace/MacGyver/reload-browser.applescript;osascript ~/workspace/MacGyver/focus-textmate.applescript" src/


You can find the reload_browser.applescript here and the focus-textmate.applescript here.

Telling time in different timezones with bash on OSX

You can use the TZ variable to affect the execution of date command.

Current time in Japan Standard Time (JST)
TZ=Asia/Tokyo date

Pacific Standard Time (PST)
TZ=America/Los_Angeles date

Eastern Standard Time (EST)
TZ=America/New_York date

Central Standard Time (CST)
TZ=America/Chicago date

Coordinated Universal Time (UTC) / Greenwich Mean Time (GMT)
TZ=Europe/London date

Central European Time (CET)
TZ=Europe/Budapest date


Here is how i use it. telltime.sh

Iterating through an array in bash

locations=( Roppongi Shibuya Ebisu )

for name in ${locations[@]}
do
  echo $name
done

Finding in files

Finding a string in files is useful and not that straightforward. But don't despair, we have bash.

find . -exec grep -q 'foobar' '{}' \; -print

This searches in the current directory including its subdirectories and finds files that contain foobar.

Monitoring file system activity on OS X

My hard disk is quite slow, so It seemed a good idea to see what's going on under the hood, why the filesystem is so busy.
I came across fslogger, which is a great user-space program that subscribes to the kernel's file system change notification service.

Sounds great and actually monitoring file system activity with fslogger is quite easy. It must be run as root but that's it.

The output is little bit verbose but you can cut it with awk.

# changed files
sudo fslogger | awk '/FSE_ARG_STRING/ { print $5 }'

# file change type
sudo fslogger | awk '/type.*=/ { print $3 }'

# process that caused the change
sudo fslogger | awk '/pid.*=.*\(.*\)/ { print $4$5 }'



Helpful.

Unix sort by column

Sort is a very useful unix utility. Simplest usage is here::

ls | sort

but that's not very interesting. Let's say we want to sort all the files by size:

ls -l | sort -k5 -n

What this command does exactly sort by 5th field using numeric order. Another useful option you may use is -t which allows you to select the field separator.