[SOLVED] sed command for matching the end character of a line and replacing the whole line.

mamunm · 04-11-2014, 03:23 PM

I have a file with multiple lines that end with either 0 or 1. now i want replace those line having 1 at last. how can i do that?
Some more question:
1)i want to replace all elements below a certain limit by a threshold value.
2)In a file i have the following line in regular interval:
energy=25
energy=35
energy=45
After each iteration it writes that value. Now i want to extract the last line.
It would be a great help if anyone kindly answer these questions.
Thanks

Ser Olmy · 04-11-2014, 05:22 PM

It certainly is possible to replace

(any number of characters)(one or more specific characters)(End-of-Line marker)

with something else. The following will replace any line ending with the character X with foo:

Code:

sed "s/.*X$/foo/"

With regards to your other questions:

1) I'm not sure I understand exactly what you want to do. Can you be a bit more specific?

2) The last line of a file can easily be retrieved with tail:

Code:

tail -n 1 < filename

mamunm · 04-11-2014, 05:28 PM

Thank you very very much. it worked nicely. actually second question is not a serious issue. i think a if statement can do that. The main thing is i want to replace all the value less than 100 by 100.

allend · 04-11-2014, 10:32 PM

Quote:

The main thing is i want to replace all the value less than 100 by 100.

Try awk instead of sed

Code:

bash-4.2$ cat en1.txt
energy=25
energy=35
energy=45
energy=125
energy=135
energy=145

bash-4.2$ awk 'BEGIN{FS=OFS="="} {if ($2<100 && $NF>1) {print $1,"100"} else  {print} }' en1.txt 
energy=100
energy=100
energy=100
energy=125
energy=135
energy=145

mamunm · 04-12-2014, 12:19 AM

I am actually a new user of Linux. For editing i was basically using vi and sed command. Thanks for introducing awk to me.