How can I count the occurrences of a string within a file

Question

Just take this code as an example  Pretending it is an HTML text file  if I would like to know the total number of times that echo appears  how can I do it using bash   new user         echo  Preparing to add a new user         sleep 2     adduser       run the adduser program    echo  1  Add user  echo  2  Exit   echo  Enter your choice    read choice   case  choice in     1  new user       call the new user   function                  exit           esac

User · Answer

None of the existing answers worked for me with a single-line 10GB file. Grep runs out of memory even on a machine with 768 GB of RAM!

$ cat /proc/meminfo | grep MemTotal
MemTotal:       791236260 kB
$ ls -lh test.json
-rw-r--r-- 1 me all 9.2G Nov 18 15:54 test.json
$ grep -o '0,0,0,0,0,0,0,0,' test.json  | wc -l
grep: memory exhausted
0

So I wrote a very simple Rust program to do it.

Install Rust.
cargo install count_occurences

$ count_occurences '0,0,0,0,0,0,0,0,' test.json
99094198

It's a little slow (1 minute for 10GB), but at least it doesn't run out of memory!

User · Answer

I m taking some guesses here  because I don t quite understand what you re asking   I think that what you want is a count of the number of lines on which the pattern  echo  appears in the given file   I ve pasted your sample text into a file called 6741967   First  grep finds the matches   james Brindle tmp grep echo 6741967      echo  Preparing to add a new user     echo  1  Add user  echo  2  Exit  echo  Enter your choice      Second  use wc -l to count the lines  james Brindle tmp grep echo 6741967    wc -l        4

User · Answer

if you just want the number of occurences then you can do this    grep -c  string to count  file name

User · Answer

This will output the number of lines that contain your search string   grep -c  echo  FILE   This won t  however  count the number of occurrences in the file  ie  if you have echo multiple times on one line    edit    After playing around a bit  you could get the number of occurrences using this dirty little bit of code   sed  s echo echo n g  FILE   grep -c  echo    This basically adds a newline following every instance of echo so they re each on their own line  allowing grep to count those lines  You can refine the regex if you only want the word  echo   as opposed to  echoing   for example

User · Answer

The number of string occurrences  not lines  can be obtained using grep with -o option and wc  word count      echo  echo 1234 echo    grep -o echo echo echo   echo  echo 1234 echo    grep -o echo   wc -l 2   So the full solution for your problem would look like this     grep -o  echo  FILE   wc -l

[bash] How can I count the occurrences of a string within a file?

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