Appending a string to a file

JStew · 03-03-2003, 08:42 PM

what command can i use that would add the string, "#! /usr/bin/perl -w" to a file?

Crashed_Again · 03-03-2003, 09:10 PM

Something like this would append a string to a file:

echo "#! /usr/bin/perl -w" >> test.txt

Carefull though. If you use one > instead of two >> then it will erase everything and just write that one line.

JStew · 03-03-2003, 09:27 PM

i will let you know if this helps... i wrote this script for my linux box and i am viewing this from windows :-(

neo77777 · 03-03-2003, 09:35 PM

it will do no good if the file isn't empty, it will append the line at the end of file, what would you need to do if you are a perl inclined person is open the file fo reading and read all the contents of the file into an array, then close it and open it again for writing and print #!/usr/bin/perl -w first and then all the every line of the array, something like this should work

Code:

 #!/usr/bin/perl
open (READ,"filename");
@lines=<READ>;
close READ;
open (FILE,">filename") or die "$!:\n";
print FILE "#!/usr/bin/perl -w\n";
foreach $line (@lines){
print FILE $line;
}
close FILE;

Tinkster · 03-03-2003, 09:37 PM

Probably won't do what you want ...

it appends the line, not prepends...

But there's vi, and with a little luck
it will even work in the sucky windows
telnet emulation :}

Cheers,
Tink

Crashed_Again · 03-03-2003, 09:42 PM

Oh very neat neo77777. I figured that the line "#!/usr/bin/perl -w" was meant to go in the beginning of the file but JStew did say "How do I APPEND to a file"

Its always neat to see some nice perl scripting. Thanks.

Tinkster · 03-03-2003, 09:47 PM

sed -e 'i#!/usr/bin/perl -w' <old_file> > <new_file>

Cheers,
Tink

cuckoopint · 03-03-2003, 10:18 PM

Quote:

Originally posted by Tinkster
sed -e 'i#!/usr/bin/perl -w' <old_file> > <new_file>

perl was soooo overkill for this task.

JStew · 03-04-2003, 06:01 AM

"perl was soooo overkill for this task."- cuckoopoint

oh... but this question is part of a bigger plan...

append...input... it's all the same damn thing :-)

arnold · 03-04-2003, 07:48 AM

no temp/intermediate files:

ex FILE <<!
0i
#! /usr/bin/perl -w
.
wq
!

neo77777 · 03-04-2003, 11:17 AM

Why I provided perl script is for the assumption that there are more than one file that needed editing, so dancing around this perl script you can edit multiple files in one shot, as for straight unix way to do it I agree sed is the most robust, and you can always use old cat to concatinate two files one being a single string file containing #!/usr/bin/perl -w and another is the perl script that required editing (file1).
echo '#!/usr/bin/perl -w'>> file2
cat file1 >> file2

arnold · 03-04-2003, 03:07 PM

"more than one file that needed editing"

for f in FILE_LIST
do
ex $f <<!
0i
#! /usr/bin/perl -w
.
wq
!
done

JStew · 03-04-2003, 03:23 PM

Tinkster wins! The sed solution is by far the most efficient one. Thanks for the help Tinkster!

Tinkster · 03-04-2003, 03:48 PM

Cheers mate, pleasure ;)

Tink