You should be able to your own counting now.The " global regular expression print" or " grep" for short is a text processing editor. echo "error 1 error 2 error 1 error 2" | grep -o -e 'error ]' | sort | uniq -cįrom this one-liner we can see that there are two of each value. Using our trusty utilities, sort and uniq, we can now count each unique result. The output should look like this: error 1 Where n is a single digit: echo "error 1 error 2 error 1 error 2" | grep -o -e 'error ] All we do is add a space and the “]” expression to search for entries that look like this: “error n”. To do this we add the “-e” argument to the grep command. We can also count unique values in a similar way as we did in our first example with a regular expression. echo "error error error error" | grep -o error | wc -l Count unique results within a line We can now pipe the output to wc to count the total number of results. echo "error error error error" | grep -o error In keeping with the error theme of the previous examples, the string is the word “error” printed multiple times. Each match will be printed on a separate line. Using the -o (–only-matching) option, grep will only output the exact match and continue searching the current line.
You can also grep for multiple occurrences within a line. I’ll just add this as a bonus, as I just learned this myself.
Grep unique r code#
This will output the number of times error code 32 appeared: 17 How do I count matches within a line? In our example, we are only interested in the number of lines. The wc command will print the number of lines, words and bytes in the text you pass to it. It is also a part of the coreutils package.
The example we just went through might be a bit too convoluted for these cases. In some cases, you might just want the total number of results. 17 ERROR: Error code 32ĥ ERROR: Error code 8 Count the total number of results from grep The results are now ordered by frequency. grep ERROR myfile.txt | sort | uniq -c | sort -nr To ensure that it is sorting by numbers, we add n, and to show the results in descending order, we add r. But this time, we will add two arguments. But it would help even more if we could see the results ordered. This is very helpful in our situation since we can see that “error code 32” was the most common message. Running this will show us each message only once with the count prepended to the line.
Grep unique r full#
So the full command will be: grep ERROR myfile.log | sort | uniq -c It also has a helpful argument to count how many duplicates there were. By default, the uniq command removes duplicates. Next, we will do the actual counting with the uniq command. This will sort all the lines and make sure each repetition appears with the lines that are like it. To do this, we first pass it through the sort command. But we want to know how often each of them appears. Now we should get only the error messages. Now we want to find all the errors in the file using grep. I have made a small mock log file, that has some simple error messages. Sort sorts the lines alphabetically, and uniq finds repetitions in the output. Both of them are a part of the GNU coreutils package and should be installed by default on any Linux distribution. There are actually two small programs that I would use in this scenario.
One example is when I need to find out how often a particular error has appeared in a log file. Sometimes you also need to count unique values that grep returns. Just finding the results is not always enough. At least in my case, I probably use grep daily. It is a quick way to find whatever you need from a text file. As a Linux admin, you will probably find yourself running grep quite frequently.
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