I have a directory with over 150K files.  I want to create a list all the files that contain the text stored in a text variable, storing that list of files in another variable .I first tried:searchtext=Subject: Yourfiles = $(grep $searchtext ./* | awk '{print ($1)}' ), and while that works for a moderate number of files in the directory, it generates an error Argument list too long when run on the directory with 150K files.  (The awk with print was used to extract just the filename from the grep result.)I found that  files=$(grep $searchtext ./* | awk '{print ($1)}') works for the 150K file directory, but it takes almost 90 minutes to run.If present in the file, the $searchtext string will be located in the beginning of the file. So I thought I could speed this up greatly if the grep was restricted to say the first 30 line of text.  Not being sure how that could be done, I found http://superuser.com/questions/667006/how-do-i-grep-the-first-50-lines-of-each-file-in-a-directory-recursively and tried several of the suggestions there.  The one that seemed best suited for my task was:searchtext=Subject: Yourfind . -type f -exec head -n 30 {} + | grep $searchtextThis runs in an acceptable time, but it does not output the filenames of the files that contain the search text.  I trred grep -l, but that results in an error:  find: head' terminated by signal 13 .  Somewhere it was suggested that the using \ instead of + might be more appropriate.  However, that also generates an error: find: missing argument to-exec' .  Looking ahead to when the grep result includes the file names, I expect another issue.  When I try to assign the grep output to a variable as:files = $(find . -type f -exec head -n 30 {} + | grep $searchtext)I get an error ut1.sh: line 16: files: command not found .  For some reason, the variable files is being interpreted as a command?  My script name is ut1.sh .  I have assigned variables this way many times before without issue.My bash version is GNU bash, version 4.1.2(2)-release (x86_64-redhat-linux-gnu)How to get the job done, and what was wrong with my attempts?thanks
For a large directory, create a variable of the filenames which include lines which include the text string stored in another variable
linux;grep