How to use pipe within -exec in find

Question

Is there any way to use pipe within an -exec in find? I don't want grep to go through whole file, but only through first line of each file.

find /path/to/dir -type f -print -exec grep yourstring {} \; 

I tried to put the pipelines there with "cat" and "head -1", but it didn't work very well. I tried to use parenthesis somehow, but I didn't manage to work out how exactly to put them there. I would be very thankful for your help. I know how to work it out other way, without using the find, but we tried to do it in school with the usage of find and pipeline, but couldn`t manage how to.

find /path/to/dir -type f -print -exec cat {} | head -1 | grep yourstring \; 

This is somehow how we tried to do it, but could't manage the parenthesis and wheter it is even possible. I tried to look through net, but couldn' t find any answers.

Answer 1

In order to be able to use a pipe, you need to execute a shell command, i.e. the command with the pipeline has to be a single command for -exec.

find /path/to/dir -type f -print -exec sh -c "cat {} | head -1 | grep yourstring" \; 

Note that the above is a Useless Use of Cat, that could be written as:

find /path/to/dir -type f -print -exec sh -c "head -1 {} | grep yourstring" \; 

---

Another way to achieve what you want would be to say:

find /path/to/dir -type f -print -exec awk 'NR==1 && /yourstring/' {} \; 

Answer 2

This does not directly answer your question, but if you want to do some complex operations you might be better off scripting:

for file in $(find /path/to/dir -type f); do echo ${file}; cat $file | head -1 | grep yourstring; done