Using Shell Variables in awk and sed

For sed - use double quotes around the variable.

sed '/'"$pattern"'/d' filename

Another option is to enclose entire sed command in double quotes.

sed "/$pattern/d" filename

For awk - use combination of double quotes single quotes double quotes

awk '{ if ($(1) == "'"$pattern"'" ) {print $2}}'

Optionally, you could create an awk variable from shell variable.

awk '{ if ($(1) == ipattern ) {print $2}}' ipattern=$pattern filename

Router Transformation Groups

Router Transformation's Groups are not the same as CASE statement conditions or what you may also call waterfall logic.

Router transformation routes data to all the groups that evaluate to TRUE unlike the CASE statement that executes the code only for the first true condition.

Awk one liner IF

Here is a quick one liner AWK for field comparison.

awk -F, '{if ($(1)=="0") {print $1}}' myfilename

What does it do?
From the comma separated file every record with first field as zero is printed.

It's important to keep parentheses as indicated. Although "print $1" is good; "if $1" poops.

Python - All Set for Comparison

I spent entire evening looking for a way to sort the characters in a string and figured it out.

1. Turn the String into List. 
2. Sort it. 
3. Join it back as a String.

And then, I stumbled upon a better way to do string comparison. Convert them to sets!!!

set(stringA).difference(stringB)

Note that it may not be same as
set(stringB).difference(stringA)

Details on set theory here:

http://docs.python.org/library/sets.html#set-objects

Discussion here:

http://stackoverflow.com/questions/1388818/how-can-i-compare-two-lists-in-python-and-return-matches

BASH shell only - brace expansion

You might have used brace expansion if you have tried this very popular way of backing up files - 

cp filename{,.bk}

The command above will copy filename to filename.bk. It saves you from writing the filename again. 

This neat stuff is not compatible with korn shell.

Some other examples to reinforce how this works.

echo John{Doe,Smith}
  JohnDoe JohnSmith
echo {John,Jane}{Doe,Smith}
  JohnDoe JohnSmith JaneDoe JaneSmith
  

Note the lack of space after comma.

vi or sed - Delete till end of line from pattern

Here's the regex that will match everything from the pattern until a newline is found.

Say you want to remove everything after "here" from this sample file.

code here    where?
code here   right here!
code here         look every where.

Used regex

s/here.*//

Explanation:

.*  

dot matches any character including spaces, numbers, alphabets but not new line.

asterisk matches any number of occurrences of a character

s/here.*/meow/ will result in

code meow
code meow
code meow




Shell script for multiple SED edits

Following shell script

1.    Reads the names of the files to be edited from the file "filelist".

2.    Executes two sed statements on each of those files and

3.    Overwrites the original file. 

#!/usr/bin
while read line
do
sed 's/0512/0505/g' $line > temp
sed 's/05\/13/05\/06/g' temp > $line
done < filelist 

Creating SQL statement for a Target Definition

I learned two things -
1. Don't blindly believe when people say it can't be done.
2. Informatica lets you create SQL statement to create target table.

I've been working to load this massive VSAM file with more than 1500 fields. Creating the source definition from the COBOL copybook was simple but creating ORACLE table manually for these many fields dampened my spirits.

I asked one of the more senior guys around here if he knew how to do it since he has been working on the same project with me. He said it wasn't possible and that I needed to do it manually.

I came back crushed and started reading Informatica Manual to delay my nemesis (so dramatic but seriously 1500 fields!).

It's then I learned that once the target definition has been created, Target Designer lets you "Generate/Execute SQL" for the target. BINGO! I was done in 2 minutes.

PS - To create target definition, I just dragged and dropped the source definition to target designer.

Automator - Get folder name using Shell Script

I wanted to move a folder from Movies to Music and rename both the folder and the videos.

Challenge was to 

1) Pass output of previous action to shell script.

2) Get the folder name.

#1 Passing output of previous action to shell script
Once you drag and drop Utilities/Run Shell Script action and change drop down "Pass Input" to "as arguments", it becomes evident that the values are passed in the usual way command line variables are passed to a shell script in Unix. i.e. in $@

If you see in the automator workflow above, I'm getting all the file names in the folder as $@ in my script. You might know that we can access the contents of $@ as $1, $2 etc and $# gives the total number of variables, in this case number of files.

Here's how I went over the list of files and renamed them all.

#Say for example $@ has "/Users/ruchi/Movies/Snowboarding 2010/videofile1.AVI /Users/ruchi/Movies/Snowboarding 2010/videofile2.AVI"
while [ ! -z "$1" ]
do
mv "$1" "`echo "$1" | sed 's/\[[aA-zZ,.]*\] [aA-zZ, ]* - [0-9][0-9] - //g'`"
shift
done

#2 Getting the folder name

This is more of a hack. I already had file names with path in #1, I checked the depth of my the folder from home (/Users/ruchi/) and used awk to get the folder name from a file name.

#for example let's say $1 has /Users/ruchi/Movies/Snowboarding 2010/videofile1.AVI
foldername=`echo "$1" | awk -F/ '{print $5}'` # That's right, not $4 but $5 due to leading "/"
echo $foldername #output: Snowboarding 2010

Here's another tutorial on how to pass variables to shell script.

Text Wrapping is Working

Many thanks to cimg's tutorial on dynamic cell height, text wrapping is working. If you want to keep the default font and size for the not-so-long data cells, keep the height fixed as 44.0f and use "initWithStyle:UITableViewCellStyleDefault" formatting on those cells.

iOS or Cocoa - lookup that method

I was feeling lost with what the parameters for a method and found the way to look it up without leaving xcode. Just CMD+double click the method.

Here's the link to thank for.
CGRectMake parameters ? « cocos2d for iPhone

And am writing this post using blogger bookmarklet (chrome addon) called "blog this". It lets you blog any webpage from that page.

Shell Variables are Global by Default

All variables in a shell script are global unless specifically declared as local. Local variables can be used only inside a function.

#!/bin/bash
# Global and local variables

carwash()
{
local vin="17DIGITS"
echo "IN Carwash. Your windscreen is:" $1 "and your VIN is:" $vin
post_carwash_status="BEARY CLEAN"
}

status="DIRTY"
carwash $status
echo "After carwash. Your windscreen is:" $status "and your VIN: " $vin
echo "Post Carwash Status: " $post_carwash_status

OUTPUT

IN Carwash. Your windscreen is: DIRTY and your VIN is: 17DIGITS
After carwash. Your windscreen is: DIRTY and your VIN: 
Post Carwash Status:  BEARY CLEAN

Notice that the local variable vin is not available outside the function.

ps to list only ppid

I generally use ps to get ppid to kill a process and finally figured a way to list just that.

ps -o ppid

And to list ppid without header, indicate that it should have a value. To display more information, add the headings preceded by output formatter -o.

ps -o ppid=
ps -o ppid= args= | grep Firefox 

vi Search backwards

For some reason I couldn't ever remember how to do a backward search in vi. So I would use forward search command, "/pattern" and then do "N" which is fine except the clumsy usage of uppercase.

Backward search can be done with "?pattern" and then do "n" to iterate over all the occurrences. Committed to memory now.