Substituição de variável em um script sed

Question

Depois de executar este código

#!/bin/bash
rm -f myfile myfile-individual
echo "Greetings, foobar!" > myfile
MYSTRING="Jack"
cat myfile | sed 's:foobar:$MYSTRING:' > myfile-individual

terminamos com

Greetings, $MYSTRING!

no myfile-individual.

Qual deve ser o script (sed / bash) para a saída ser

Greetings, Jack!

    

Answer 1

Altere as aspas simples para aspas duplas. E solte o gato (UUoC):

sed "s:foobar:$MYSTRING:" myfile > myfile-individual

Na manpage do bash:

   Enclosing characters in single quotes preserves the  literal  value  of
   each character within the quotes.  A single quote may not occur between
   single quotes, even when preceded by a backslash.

   Enclosing characters in double quotes preserves the  literal  value  of
   all  characters  within the quotes, with the exception of $, ', \, and,
   when history expansion is enabled, !.  The characters $  and  '  retain
   their  special meaning within double quotes.  The backslash retains its
   special meaning only when followed by one of the following  characters:
   $,  ',  ", \, or <newline>.  A double quote may be quoted within double
   quotes by preceding it with a backslash.  If enabled, history expansion
   will  be  performed  unless an !  appearing in double quotes is escaped
   using a backslash.  The backslash preceding the !  is not removed.

    

Answer 2

sed -i 's|foobar|$MYSTRING' myfile-individual 

Isto irá fazer a substituição, bem como escrevê-lo no arquivo