Skip to main content

A cookbook on regular expressions and bash scripts

Since I started using this for searching strings I cannot dream of using anything else. I will put down some of the usual scripts I use wither with MINGW shell or Cygwin or even oracle to search data in a file or an oracle database.Think of it as a how to manual.

1. (Mingw) You want to filter the files on the command line which match two words?

Here I try to match the word FR_BLOCK and word starting with C from a list of files.

ls -lf | grep -iE "FR_BLOCK"| grep -iE "^C"

What this does is divided into 3 parts

ls -lf will list the directory contents in long format and remoe all extra information like date of creation and file size etc.

grep -iE "FR_BLOCK" The output of above command is piped to grep via | operator. The grep command will search for FR_BLOCK word and assumes matching with or without capital letters(i) and uses extended regular expressions(E).

The third part of grep -iE "^C" will search the piped out of the above command and searches for the file name where the starting alphabet is a C.

2. (Mingw) You want to know the time when a particular file has changed?

Use commands stat, grep and cut. For example here I find the time when the file filetime.sh has changed.

stat filetime.sh | grep 'Change:' | cut -f 3 -d ' '

stat will report a whole bunch of stats of the file. grep will return the line where word 'Change:' exists and cut commadn will cut the retunred string from grep into fileds (-f) at the 3rd point and assumes a delimiter (-d) of single space (' ').

3. (Mingw) You want to search for files and directories which end with 15 or 5 or 1

ls -l | grep -iE '[15]$'

Comments

Popular posts from this blog

Basic Econometrics - Chapter 1 - Exercise 1

Exercise 1.1 Table 1.2 gives data on the Consumer Price Index (CPI) for seven industrialized countries with 1982-1984 = 100 as base of the index. a. From the given data, compute the inflation rate of each country. b. Plot the inflation rate for each country against time (i.e. use the horizantal axis for time and the vertical axis for the inflation rate) c. What broad conclusions can you draw abou the inflation experience in the seven countries? d. Which countries inflation seems to be most variable? Can you offer any explanation? ## Note here I have to skip several rows and add column names. Have a look at ## the raw data. Column names are c('Year', 'Canada', 'France', 'Germany', ## 'Italy','Japan', 'UK', 'US') cpi <- read.table("https://raw.githubusercontent.com/cablegui/Econometrics/master/OriginalData/Table%201.2.txt", skip = 6, col.names = c("Ye...

Step by step guide to installing and using miktex with RStudio (Windows)

Using miktex with Rstudio is very easy with the miktex portable app available from http://miktex.org/portable. Steps 1. Follow the instructions from http://miktex.org/portable to download and unzip the miktex portable application in a loccation of your choice. 2. In R write the following code in a script and save it. Note that the E:\\Software-Silo\\Miktex\\miktex\\bin location is the location where I unzipped the miktex portable application. # Install miktex y <- Sys.getenv("PATH") x <- paste0(y,";","E:\\Software-Silo\\Miktex\\miktex\\bin") Sys.setenv(PATH=x) 3. Run Miktex by double clicking the following application "miktex-portable.cmd" in the Miktex main directory. 4. Run step 2 in RStudio to install the path into R environment. 5. Open a new RNW in RStudio to test whether Miktex works . 6. Run Compile PDF in RStudio. It should be just at the top of the RNW file created in step 5. 7. You will now see a PDF file whic...

Installing and using ROracle in R

Hi, Hope this post keeps you in the best of health. I am an oracle user and wanted to know how to fetch database information in R. There is a package out there called ROracle but there are no binaries for it and it thus needs to be built and then installed. Here are the steps to install it on Windows 7 machines. 1. Download the package from http://cran.r-project.org/web/packages/ROracle/index.html. Since I wrote this post the latest that was available was  ROracle_1.1-12.tar.gz . 2. Place the package in the directory where R is installed. I placed mine in E:\R\R-3.0.2\bin folder. 3. Install RTools from http://cran.r-project.org/bin/windows/Rtools/. Since my R version is R-3.0.2 the toolkit I needed was RTools31.exe. 4. Install the Rtools software in the R home directory. I placed mine in E:\R\Rtools. Place all the extras in there too. For example I placed my 32 bit extras in E:\R\RExtras32 and the 64 bit in E:\R\RExtras64 folder. These extras are not necessary for ...