[SOLVED] Very new to Linux/Trying to understand the Sed command

kayjay1 · 02-27-2011, 11:32 AM

I have tried to get the desired outcome and have failed.

the blue cat was chased by the brown dog
the blue cat was not chased by the brown dog

Line should read

the blue snake was chased by the brown snake
the blue car was not chased by the brown car.

I got the first line, but the words to be substituted in the second line did not change.

sed -e 's/cat/snake/' -e 's/dog/snake/' -e '/not/s/cat/car' -e 's/dog/cat/'

I have read and found that sed does not handle long line of command, so is there some way to break this up. I tried to use pipe and \n. Very new to this.

paulsm4 · 02-27-2011, 12:25 PM

Hi -

No, the length of the line is not the problem.

Quote:

vi test.txt

Code:

the blue cat was chased by the brown dog
the blue cat was not chased by the brown dog

Quote:

sed -e 's/cat/snake/' -e 's/dog/snake/' -e '/not/s/cat/car' -e 's/dog/cat/' test.txt

Code:

sed: -e expression #3, char 14: unterminated `s' command

Quote:

sed -e 's/cat/snake/' -e 's/dog/snake/' -e 's/dog/cat/' test.txt

Code:

the blue snake was chased by the brown snake
the blue snake was not chased by the brown snake

Quote:

sed -e 's/cat/snake/' -e 's/dog/snake/' -e 's/dog/cat/' -e 's/not chased by the brown snake/not chased by the brown car/' test.txt

Code:

the blue snake was chased by the brown snake
the blue snake was not chased by the brown car

kayjay1 · 02-27-2011, 01:07 PM

Thank you very much. Can you also try to help me understand this. I under the the first, second, and last expression. The third substitution has me stumped. -e 's/dog/cat'
I forgot to add the file name at the end of my line. I apologize for that. Thank you again.