sed searching across lines

miechu · #1 (**permalink**) 09-25-2006

hi,

i'm making now a bash script, that runs some compiler... i want to take only errors form its output eg:

output:

Code:

bla bla bla
...
erros is 1324546
the bla bla bla 

bla bla bla...
...

and i want to get only

Code:

erros is 1324546
the bla bla bla

i've managed to do something like this:

Code:

cat errors_file | sed -n "N;s/errors.*\n/&/P"

but i don't know how to do something like (.*\n)* how can this be done?

aigles · #2 (**permalink**) 09-25-2006

Try this:

Code:

sed -n '/erros is/{N;p;}' errors_file

Jean-Pierre.

miechu · #3 (**permalink**) 09-25-2006

this is not exactly what i want... becouse i don't know how many lines error will have... all i know it beigns with:"errors is" and ends with ^$

#edited

and can you explain what your command does? as i understand it it will print out the maching line and the one follwing it... but why this strange syntax? why do you do some {} at the end? where is s/?

aigles · #4 (**permalink**) 09-25-2006

Quote:

this is not exactly what i want... becouse i don't know how many lines error will have... all i know it beigns with:"errors is" and ends with ^$

In that case :

Code:

sed -n '/erros is/,/^$/p' errors_file

Quote:

and can you explain what your command does? as i understand it it will print out the maching line and the one follwing it... but why this strange syntax? why do you do some {} at the end? where is s/?

/error is/{ ... }
Select lines that contains 'erros is' and execute commands '...'
N;p
Append next line to current line and print the whole

Jean-Pierre.

miechu · #5 (**permalink**) 09-25-2006

cooooooooool

this is great

can you explain me this command?

btw. big, big biiiiiiiiig thanks

aigles · #6 (**permalink**) 09-25-2006

From sed man page :

Quote:

A command line with two addresses separated by commas selects the entire
range from the first line that matches the first address through the next
line that matches the second. (If the second address is a number less than
or equal to the line number first selected, only one line is selected.)
Thereafter, the process is repeated, looking again for the first address.

/erros is/,/^$/p
First line contains 'erros is' and last line is empty.

Jean-Pierre.

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