text-processing

Joining two files with unique identifier

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I have two files with approximately 12900 and 4400 entries respectively, that I want to join. The files contain location information for all landbased weather observing stations around the globe.
The largest file is updated biweekly, and the smaller once a year or so. The original files can be found here (http://www.wmo.int/pages/prog/www/ois/volume-a/vola-home.htm and
http://weather.rap.ucar.edu/surface/stations.txt). The files I have are already manipulated by me with some mixed awk, sed, and bash script. I use the files to visualize data using the
GEMPAK package, that is freely available from Unidata. The largest file will work with GEMPAK, but only not with its full capability. For this a join is needed.

Is there any alternative to grep’s -A -B -C switches (to print few lines before and after )?

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grep -A 2 -B 3 prints 2 lines after the grep string and prints 3 lines before. grep -C 3 prints 3 Lines before and 3 lines after Unfortunately, the grep I’m using does not support these options. Are there any alternative commands or script available to simulate this? Using sed/awk/perl/shell scripts? Answers: Thank you … Read more

What is the difference between > and >> (especially as it relates to use with the cat program)?

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Suppose that I have a file called temp.txt. Using the cat program, I would like to add the contents of this file to the end of myfile.txt — creating myfile.txt if it does not exist and appending to it if it does. I am considering these possibilities: cat temp.txt > myfile.txt or cat temp.txt >> … Read more