sed-append question

[Gemini_2]

I have the following input

load /BC/TOC1
load /BC/TOC2

I want to add one more load after the last one, in this case: "load BC/TOC2"

sed "/^load/a\load /BC/TOC3" $file

it runs the sed twice :-( like the following
load /BC/TOC1
load /BC/TOC3
load /BC/TOC2
load /BC/TOC3


how do I change the sed statement to only append to the last one?

the desired output will be
load /BC/TOC1
load /BC/TOC2
load /BC/TOC3

thank you

[Abhijeet_3]

Alternative way is
echo " load/BC/TOC3" >> filename

Abhijeet

[Gemini_2]

it will not work because I have other stuff in the file. I just show you guys the portion of the file that I want to modify.

[James R. Ferguson]

Hi Gemini:

Try:

# cat ./append
#!/usr/bin/sed -f
n
/^load TOC2/p
a\
load \/BC\/TOC3

...run as:

# ./append file

Regards!

...JRF...

[James R. Ferguson]

Hi (again):

Sorry, that should look like:

# cat ./append
#!/usr/bin/sed -f

#!/usr/bin/sed -f
/^load \/BC\/TOC2/{
a\
load \/BC\/TOC3
}

...run as:

# ./append file

Regards!

...JRF...

[Gemini_2]

sorry, I am still not making myself clear.

the last entry may not always be /BC/TOC2, it can be /BC/TOC3, /BC/TOC4, the whole point is how to append the new entry just ONCE?

thank you

[James R. Ferguson]

Hi Gemini:

# cat ./append
#!/usr/bin/sed -f
${
a\
load \/BC\/TOC_
}

# ./append file

...will append to the file's end.

Regards!

...JRF...

[Gemini_2]

are you sure?

is the difference between yours and mine the "_"? I still get the same result :-(

please help out...

[James R. Ferguson]

Hi:

Well, mine works for me, so try this variation:

# #!/usr/bin/sed -nf
p
${
a\
load \/BC\/TOC_
}

...substitute anything you want for "TOC_".

Regards!

...JRF...

[Dennis Handly · Accepted solution]

I don't think you can use sed at all. Also, do you have more than one sequence of loads that can be present? If so, you can't even use awk unless you make a grep -n prepass:

#!/usr/bin/ksh
FILE=itrc_append

# fine last "load"
line=$(grep -n "^load" $FILE | tail -1 | sed 's/:.*$//')

# add one "load /BC/TOC3" after the last "load".
sed -e "${line}a\\
load /BC/TOC3" $FILE

[Gemini_2]

okay....

I should give a complete file to make my point clear

the file is like

----------------------
load /BC/TOC1
load /BC/TOC2

description: testing
vob: bc
---------------------

so, I can not just append at the end of the file..I need to append at the end of the load statement..

the solutions above are all at the end of the file.....

[Dennis Handly]

>the solutions above are all at the end of the file.....

Mine is not. I find the LAST "load" and add after it.

[Sandman!]

Try the sed command below. It inserts the line "load /BC/TOC3" right after the last load line in the input file.

sed '
/^load/,/^$/{
/^$/{i\
load /BC/TOC3
}
}' infile

~hope it helps

[Dennis Handly]

Sandman's seems to work only if there is a blank line after the load. Mine works no matter how many blocks of "load"s or what follows them.

[Gemini_2]

Thanks for Dennis Handly's solution. that works very well.

I also like Sandman's solution, but I have question about your synatx

sed '
/^load/,/^$/{
/^$/{i\
load /BC/TOC3
}
}' infile

1.what does the first/second line mean?

I am confused at
/^load/,/^$/{
/^$/{i\

that is a new synatax to me..

please kindly shed some light..

[Dennis Handly]

>1.what does the first/second line mean?

Basically for all lines from the first "load" to a blank line, do the {} block. Inside the block it tests to make sure it is on the blank line and if so, insert.

[Sandman!]

My sed solution was based on the input file you had provided i.e

----------------------
load /BC/TOC1
load /BC/TOC2

description: testing
vob: bc
----------------------

>I am confused at
>/^load/,/^$/{
>/^$/{i\

...it's a nested sed construct which applies commands at a particular address which is within the selected block. So the above command grabs all lines that start with the word load (^load) upto the first blank line (^$). Once it reaches the blank line it inserts the desired line above the blank one.

hope it helps!