There are a few other uses of cat too, but it's outside the scope of this question. Use cat only when concatenating data (that's what its main use is). To say that standard input should come from the test.txt file and that standard output should go to the q1.txt file Even if it wasn't able to open test.txt by itself, one could have written grep -i "osx" q1.txt You can also do: grep -w 'OK' which will only match a whole word 'OK', such as '1 OK' but won't match '1OK' or 'OKFINE'. That pattern will depend upon what your whole file contents might look like. Is useless as grep is perfectly capable of reading from a file by itself (as seen above). You want to choose a pattern that matches what you want, but won't match what you don't want. The extreme example of that would be: cat test.txt | cat | cat | cat | grep -i "osx" | cat | cat >q1.txtīut even just cat test.txt | grep -i "osx" >q1.txt There is something often referred to as "useless use of cat" (or sometimes "UUoC"), which means that a cat invocation may be completely removed and that the file may instead be read directly by another tool. In the end, all lines in test.txt that contains the string osx will be outputted to the terminal. However, since you're giving grep a file to read from, it will totally ignore whatever cat is sending it. cat will read from q1.txt and try to write it to its standard output, which is connected to the standard input of grep. What this actually does is to start cat and grep concurrently. grep -w 1.2.3.4 testfile.csv 1.2.3.4,Jim,Jonson,000000 1.2.3.4.5,George,Doe,FFFFF How can I make it match exactly and only the specific word In this example only 1.2.3.4. Your command: cat q1.txt | grep -i "osx" test.txt If you wish to append the output at the end of the file, use > rather than > as the redirection operator. fixed FALSE, perl FALSE: use POSIX 1003.2 extended regular expressions (the default).
#Aix grep exact match how to
After going through all the commands and examples, you will learn how to use grep to search files for a text from the terminal. perl TRUE: use Perl-style regular expressions. Introduction This guide details the most useful grep commands for Linux / Unix systems. Each of these functions operates in one of three modes: fixed TRUE: use exact matching. If the file q1.txt exists, it will be truncated (emptied) before the output is stored in it. Details Arguments which should be character strings or character vectors are coerced to character if possible.
This will search for lines in test.txt containing the string osx (case-insensitively), and store those lines in q1.txt. You may drop the cat completely, and then you should redirect the output from grep to the result file: grep -i "osx" test.txt >q1.txt
0 kommentar(er)
