replace and store a value in the same file, shell - bash

Question

How can I replace the value of a column and store the output into the same file?
example input, file:
#car|year|model
toyota|1998|corrola
toyota|2006|yaris
opel|2001|corsa
replace "corrola" with "corrolacoupe"
and store it to the input file
#car|year|model
toyota|1998|corrolacoupe
toyota|2006|yaris
opel|2001|corsa
I have tried this
awk -F '|' -v col=$column -v val=$value '/^[^#]/ FNR==NR {print $col = val }' OFS='|' $FILE >> $FILE

Answer 1

To simply replace the value in (row,col) with a new value:
$ awk -F'|' -v OFS='|' -v row=2 -v col=3 -v val=corollacoupe 'NR==row {$col=val} 1' file
#car|year|model
toyota|1998|corollacoupe
toyota|2006|yaris
opel|2001|corsa
This will set the value of input field col to val, but only in the input record row. The 1 in the end will ensure each record is printed by default. Input and output field separators are set via -F option and OFS variable.
If you need to make these changes in-place, create a temporary output file and then copy it over the original:
$ awk ... file >file.tmp && cp file{.tmp,}
Alternatively, in GNU awk, you can use the inplace library via -i inplace option:
$ awk -i inplace -F'|' -v OFS='|' -v row=2 -v col=3 -v val=corollacoupe 'NR==row {$col=val} 1' file
If you wish to skip the comments, and count only non-comment rows:
$ awk -F'|' -v OFS='|' -v row=1 -v col=3 -v val=x '/^[^#]/ {nr++} nr==row {$col=val} 1' file
#car|year|model
toyota|1998|x
toyota|2006|yaris
opel|2001|corsa

Answer 2

An ed solution that modifies the file in-place without any temporary files could be something like:
ed "$FILE" <<< $',s/|corrola$/|corrolacoupe/g\nw'
which uses an ANSI-C string to prevent special characters from being treated specially, then matches |corrola at the end of any line and replaces it with |corrolacoupe. Then we issue the w command to ed to have it write the file back out

Answer 3

A really simple solution.
darby#Debian:~/Scrivania$ cat file
#car|year|model
toyota|1998|corrola
toyota|2006|yaris
opel|2001|corsa
darby#Debian:~/Scrivania$ sed -ri 's#^(.+)\|(.+)\|corrola$#\1|\2|corrolacoupe#' file
darby#Debian:~/Scrivania$ cat file
#car|year|model
toyota|1998|corrolacoupe
toyota|2006|yaris
opel|2001|corsa
darby#Debian:~/Scrivania$