Checking and replacing first line in text file, one-liner?


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# 1  
Checking and replacing first line in text file, one-liner?

Hello,
I'm looking to check only the first line of a file to see if it is a format string, like

Code:
# -*- coding: utf-8; mode: tcl; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -\*- vim:fenc=utf-8:ft=tcl:et:sw=2:ts=2:sts=2

if the first line is anything else, insert the above string.

I'd appreciate a one liner as I'm putting this command inside of a

Code:
find . -depth -name "*.tcl" -type f -writeable ! -executable -exec awk INSERT_COOL_LINER

so far I'm hacking awk that looks like
Code:
awk 'NR==1 && /^#./ {print "format string exists";exit 1} {print "no format string";exit 1}' test.tcl

which correctly detects if the format string is there or not but can't seem to figure out how to get awk to redirect the pipe to insert the format string?

Thanks
# 2  
gnu?
Code:
string='# -*- coding: utf-8; mode: tcl; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -\\*- vim:fenc=utf-8:ft=tcl:et:sw=2:ts=2:sts=2'

sed -i '1{/^#./! s/.*/'"$string"'/}' test.tcl

This User Gave Thanks to rdrtx1 For This Post:
# 3  
Quote:
Originally Posted by rdrtx1
gnu?
Code:
string='# -*- coding: utf-8; mode: tcl; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -\\*- vim:fenc=utf-8:ft=tcl:et:sw=2:ts=2:sts=2'

sed -i '1{/^#./! s/.*/'"$string"'/}' test.tcl

Sweet! Thanks.
# 4  
Did you want to replace the first line or insert before it? If the latter, try
Code:
sed  -i -e "1{/^#./! i$string" -e"}" file

or
Code:
sed  -i -e "1{/^#./! s/.*/$string\n&/" -e"}" file

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