insert variable top of file

bishop2001 · 12-02-2015, 03:07 PM

greetings,
I'm trying to insert a variable to the top a file like below, although the variable isnt being interpolated. Suggestions please? Thanks,

STRING="Top Line Of The File"
sed -i '1i"$STRING" Today\' file

danielbmartin · 12-02-2015, 03:33 PM

Code ...

Code:

echo; echo "InFile" ...; cat $InFile; echo "End Of File($(wc -l <$InFile) lines)"
STRING="New Top Line"
sed -i "1i$STRING Today\\" $InFile 
echo; echo "InFile" ...; cat $InFile; echo "End Of File($(wc -l <$InFile) lines)"

Result ...

Code:

InFile ...
apple
banana
cherry
End Of File(3 lines)

InFile ...
New Top Line Today
apple
banana
cherry
End Of File(4 lines)

Daniel B. Martin

NevemTeve · 12-03-2015, 04:41 AM

Code:

INSERT_THIS='-n Anything $ \ can be `here/ so forget sed(1)'

(printf "%s\n" "$INSERT_THIS"; cat "file") >tmpfile.$$
mv tmpfile.$$ "file"

pan64 · 12-03-2015, 05:55 AM

Quote:

Originally Posted by bishop2001

STRING="Top Line Of The File"
sed -i '1i"$STRING" Today\' file

Code:

sed -i '1i"$STRING" Today\' <= you must not escape the closing '
# between ' ' the variables will not be expanded, you ought to use " instead:
sed -i "1i\"$STRING\"" file
# but probably you will not need that \" pair at all.

Finally as it was mentioned, you do not need sed, just something like this:

Code:

(echo $FIRST_LINE; cat file) > new_file

NevemTeve · 12-03-2015, 06:28 AM

(Finally, as it was mentioned, echo(1) should be avoided, use printf(1))