string manipulation

[mannahazarika]

suppose i want to find a pattern with grep, sed or awk,is there any way by which i can print what is in the right hand side of that pattern till the end of the line omitting the left side

[jim mcnamara]

Please give us a simple example:
Your regalar expression
expected input
expected output

Your explanation is not clear at all.

[mannahazarika]

oh i have found that out. but now i am stuck in something else.

if i want to print just the 2nd or 3rd or in general the nth occurance of a pattern is it possible to do it?

let me give an example. suppose the file 'sample.txt' contains the following lines:

this is line no.1
this is line no.2
this line contains the pattern
this is line no.4
this is line no.5
even this line contains the pattern
this is line no.7
do not forget this line for pattern
this is line no.9

grep 'pattern' sample.txt

will print all the lines viz.:-

this line contains the pattern
even this line contains the pattern
do not forget this line for pattern

Now if I want to find the second occurance of 'pattern' is there any way to do it?
i.e. just the line
even this line contains the pattern

[Dolda2000]

The most obvious (to me) method would be something like this:

grep pattern | tail -n+2 | head -n1

Just change -n+2 to -n+3 or -n+4 or whatever occurance you want

[Dolda2000]

On another note, if you want to save all the occurances by position to be able to reference them later, you can use a bash array, like this:

IFS=$'\n' res=($(grep pattern sample-file))

echo "Number of occurances found: ${#res[@]}"
echo "The first occurance was \"${res[0]}\", and the third was \"${res[2]}\""
echo "In order, the occurances were:"
for r in "${res[@]}"; do echo "  $r"; done

[mannahazarika]

thanks dolda, i didn't know head and tail had such nice options.
there lies the beauty and power of linux. by combining simple commands we can perform some mammoth tasks.

[scm]

That's the way UNIX was designed back in the late 60s! It's stood the test of time, wouldn't you say?