UNIX interview questions

1. Display 5th line of a file.

cat <file> | head -5 | tail -1

2. How to reverse a string in unix?

echo "reverse this string!" | rev

3. How to select last word of a line?

echo "i need the last word" | rev | cut -f1 -d' ' | rev

4. Select nth value from a comma seperated line.

echo "a,b,c d,e,f,g ,h"| cut -f<n> -d','

5. How to insert a header record to a file.

sed -i "1i HEADERTEXT" <outputfile>

Comments

Excel : How to pad zeros

Today I got a requirement to format the number in excel cell - to left pad number with zeros.i find the following function very useful to do it. In case one to make the number left padded with "0" s give the formula =TEXT(A1,"0000") In case two even more enhanced form to make it left padded with "0" and add two decimal places give the formula as =TEXT(A2,"0000.00")

Mount an iso image in ubuntu using no GUI

We can easily mount an iso image file in our system to a directory in linux.We need not require an GUI application to do this.It is easy to do from the terminal itself. We use the mount command for that. The steps are as follows 1. Open the terminal in ubuntu (Shortcut press ctrl+Alt+t) 2. Create a directory to mount the iso image $sudo mkdir /media/myimage 3. Then type the following command $sudo modprobe loop 4.After that go to the location of the iso image file and type $sudo mount /media/myimage -t iso9660 -0 loop The iso file is mounted to the specified directory To unmount it give the command sudo unmount /media/myimage That all.Cool isn't! sudo modprobe loop will loads the module for loopback file system iso9660 is the file system used by CD-ROM -t specify the file system type -o loop additional option used by a loopback filesystem

How to add fonts in Ubuntu?

To add fonts like Times New Roman , Ariel etc in Ubuntu do the following. 1. open ubuntu Software Center 2. Searh fo r ttf-mscorefonts in search bar. 3. Install the item listing in the page. Now you can use new fonts in ubuntu.

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