I'm chaining together multiple commands on the command line. Is there any tool that will allow me to capture output starting with a specific pattern? For example, if I have the following output produced:
line 1
line 2
line 3
line 4
my_pattern
line 5
line 6
line 7
Is there some command that will allow me to capture the output starting with my_pattern? This result in the lines
my_pattern
line 5
line 6
line 7
being captured. The my_pattern line is not mandatory to be included.
Sure, use sed like this:
sed -n '/my_pattern/,$p' file
my_pattern
line 5
line 6
line 7
That says, don't print anything (-n) till you find my_pattern, then print from there to the end of the file. Or in a pipeline:
.... | sed -n '/my_pattern/,$p'
You can use awk like this for this output redirection:
tail -f /logs/apache_error.log | awk '!found && /my_pattern/{found=1} found'
This awk will not produce any output until my_pattern is found in output and once my_pattern appears then all the output text from tail -f will be written to stdout (can be redirected to a file as well).
Testing:
printf "1\n2\n3\n4\nmy_pattern\n5\n6\n7\n" | awk '!found && /my_pattern/ {found=1} found'
my_pattern
5
6
7
