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Old 04-14-2004, 10:42 PM   #1
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Inserting Text

Does anyone know if and how it would be possible to go through many files and add a few lines of text at a certain position in the file?

Weird I realize...but worth a shot...

Old 04-15-2004, 01:01 AM   #2
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I'm not the greatest at shell programming, but here's a shot at it. Others can feel free to verify or correct it:

echo `head -c 5000 original_file` this is new text `tail -c +5000 original_file` > new_file

That's assuming the new text should go after the 5000th character in the original_file.
Old 04-15-2004, 07:33 AM   #3
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I haven't tried it yet, but I was thinking, concatenate would almost work,

cat File1 File2

Prints the combination to standard output, but what I need it to do is print it to File2, which is a devastating error. I guess it writes the first file to ouput and clears everything that was there, and then if the second file is also the output, it reads what was written to output, and just adds it, effectively duplicating.

I could write it to a new file, but then i have to copy files after anyways, no gain.

I'll give that code a shot though.

Old 04-15-2004, 10:23 AM   #4
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You can apend text to the end of a file easily with the redirection >>

echo 'Text to be inserted' >> file.txt
Old 04-15-2004, 11:11 AM   #5
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If you want to do something more advanced you can read up on sed.

Examples of what sed can do:

insert Hello World just before line 3:

sed "3iHello World" file > output

insert Hello World just before any line containing the string "foo":

sed "/foo/iHello World" file > output

You get the idea... try 'man sed'

Old 04-15-2004, 03:45 PM   #6
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sed looks like it could be a lot of fun and potentially very powerful.
BUT, the man page is about as readable as a greek dictionary.

I'm attempting to look for a bit of a tutorial...anyone know of one?

Old 04-15-2004, 04:15 PM   #7
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Originally posted by wildcat22
...the man page is about as readable as a greek dictionary.
Nothing wrong with greek dictionaries ...

andra'gathon alaethos men genestai chalepon...

Get a hold of Ellie Quigley's book
UNIX Shells by Example

She covers sed & awk in a pretty pictorial
way, describing features and their use very
well ...

Old 04-15-2004, 05:37 PM   #8
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Old 04-25-2004, 07:51 AM   #9
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#WARNING: This is untested code.
for FILE in file1 file2 file3
dd if=$FILE of=tempfile bs=1 count=100
cat insertfile >> tempfile
dd if=$FILE of=tempfile2 bs=1 skip=100
cat tempfile2 >> tempfile
mv $FILE $FILE.bak
mv tempfile $FILE
rm -f tempfile2

I'm sure there is a utility just for this sort of thing but right off the top of my head I come up with this kludge.

You take the first 100 bytes of $FILE and put in tempfile. Then add insertfile. Then add the rest of $FILE. Rename everything and get rid of the mess you made. To insert somewhere else in the file just change count and skip.


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