topic Re: sed - insert text beforecertain line in Operating System - HP-UX

sed - insert text beforecertain line

Piotr Kirklewski — Fri, 11 Dec 2009 19:44:21 GMT

Hi there
I need to place a text inside many php scripts.
I have no problem with replacement:

sed -i s/patern/replacement/ /file

But now before: "$conn = mysql_connect("
I need to insert three lines:

$MYSQL_PASSWORD = "xxx";
$MYSQL_USERNAME = "root";
$MYSQL_HOST="127.0.0.1";

How can I do that ?

Reagrds

PEter

Re: sed - insert text beforecertain line

James R. Ferguson — Fri, 11 Dec 2009 19:59:59 GMT

Hi Peter:

I'd use a simple Perl script:

# cat ./filter
#!/usr/bin/perl -p
m{"\$conn = mysql_connect\("} and print <\$MYSQL_PASSWORD = "xxx";
\$MYSQL_USERNAME = "root";
\$MYSQL_HOST="127.0.0.1";
EOF

...and given a file like:

# cat .myfile
This is my file
"$conn = mysql_connect("
this follows the $conn line...

...running:

# ./filter ./myfile
This is my file
$MYSQL_PASSWORD = "xxx";
$MYSQL_USERNAME = "root";
$MYSQL_HOST="127.0.0.1";
"$conn = mysql_connect("
this follows the $conn line...

Regards!

...JRF...

Re: sed - insert text beforecertain line

Bob E Campbell — Fri, 11 Dec 2009 23:56:45 GMT

To answer in sed:

$ cat foo
A
B
C
D
$ sed -e '/B/i\
BEFORE\
Also before' foo
A
BEFORE
Also before
B
C
D

Re: sed - insert text beforecertain line

Piotr Kirklewski — Sat, 12 Dec 2009 03:47:13 GMT

Hi
Your solution seams to be working but the date is only being displayed on the screen - doesn't go to the file. How to accomplish that ?

Re: sed - insert text beforecertain line

Piotr Kirklewski — Sat, 12 Dec 2009 03:47:58 GMT

Not date but data or text.

Re: sed - insert text beforecertain line

Hein van den Heuvel — Sat, 12 Dec 2009 03:57:15 GMT

Just redirect the output to a new file name,
or when opting for the perl solution opt for the -i = inplace edit option.

# perl -pe 'program' in > out

or

# perl -p -i -e 'program in-and-out

Try on test files first!

Hein

Re: sed - insert text beforecertain line

Piotr Kirklewski — Sat, 12 Dec 2009 04:13:54 GMT

root@fog:~# cat test
A

B

C

D

sed -e '/B/i\BEFORE\' test
A

BEFORE
B

C

D

So it does what I want except it sends the output to the standard output.
I was trying to redirect the output back to my file.

root@fog:~# sed -e '/B/i\BEFORE\' test > test

And all the text inside the file is wiped out.

:(

root@fog:~# cat test

Re: sed - insert text beforecertain line

Dennis Handly — Sat, 12 Dec 2009 06:39:57 GMT

>I was trying to redirect the output back to my file.
> sed -e '/B/i\BEFORE\' test > test
>And all the text inside the file is wiped out.

You can't do that. You must use a separate file then mv it back.
sed -e '/B/i\BEFORE\' test > test.new
mv test.new test

(GNU sed has a -i option for inplace editing.)

Re: sed - insert text beforecertain line

James R. Ferguson — Sat, 12 Dec 2009 14:26:46 GMT

Hi (again):

> I was trying to redirect the output back to my file.
> sed -e '/B/i\BEFORE\' test > test
> And all the text inside the file is wiped out.

As Dennis noted, you can't do that! I'm surprised you thought you could. The redirection occurs first, and hence the input file is immediately truncated. You must redirect to a new file; perform the 'sed' and then move the new file (output) over the old file (input) replacing the old file with its modified copy.

So it seems that you were using a GNU 'sed' when you said:

> I have no problem with replacement:
> sed -i s/patern/replacement/ /file

HP-UX's 'sed' doesn't offer that ability. As Hein noted, you could have added the '-i' option to my Perl script to perform an in-place update. In fact, you could change the first line of my script from:

#!/usr/bin/perl -p

... to:

#!/usr/bin/perl -p -i

...to update in-place; or:

#!/usr/bin/perl -p -i.old

...to update in-place while preserving the original file with a ".old" suffix. This is akin to the GNU 'sed'.

Regards!

...JRF...

Re: sed - insert text beforecertain line

Bob E Campbell — Mon, 14 Dec 2009 19:02:19 GMT

My apologies, I did not consider the file manipulation an issue to be discussed. I thought that the sed syntax of needing newlines was the important part.

I would just explicitly use a temp file.