You could also use perl, which should support \b on all platforms. Assuming your list of replacements is in the format you show (separated by ->), you could do:

perl -F"->" -ane 'chomp;$rep{$F[0]}=${$F[1]}; 
                  END{open(A,"file"); 
                    while(<A>){
                        s/\b$_\b/$rep{$_}/g for keys(%rep); 
                        print
                    }
                  }' replacements

###Explanation

• The -a makes perl run like awk, automatically splitting fields into the array @F so $F[0] is the 1st field, $F[1] the second etc. The -F sets the input field separator, just like -F in awk. The -n means "read the input file, line by line and apply the script given by -e to each line".

• chomp : removes newlines (\n) from the end of the line.

• $rep{$F[0]}=${$F[1]}; : this populates the hash %rep making the pattern to be replaced (the first field, $F[0]) the key and the replacement ($F[1]) the value. * END{} : this is executed after the input file (replacements) has been read.

• open(A,"file") : open the file file for reading with filehandle A.

• while (<A>) : read the file line by line.

• s/// for keys(%rep) : this will iterate through all the keys of the %rep hash, saving each key as the special variable $_. The s/// is the substitution operator and is making the same substitution as explained in Michael's answer.

You could also read through the file and use sed as shown in the other answers:

$ sed 's/->/\t/' replacements | 
    while IFS=$'\t' read from to; do sed -i "s/\b$from\b/$to/g" file; done

You could also use perl, which should support \b on all platforms. Assuming your list of replacements is in the format you show (separated by ->), you could do:

perl -F"->" -ane 'chomp;$rep{$F[0]}=${$F[1]}; 
                  END{open(A,"file"); 
                    while(<A>){
                        s/\b$_\b/$rep{$_}/g for keys(%rep); 
                        print
                    }
                  }' replacements

###Explanation

• The -a makes perl run like awk, automatically splitting fields into the array @F so $F[0] is the 1st field, $F[1] the second etc. The -F sets the input field separator, just like -F in awk. The -n means "read the input file, line by line and apply the script given by -e to each line".

• chomp : removes newlines (\n) from the end of the line.

• $rep{$F[0]}=${$F[1]}; : this populates the hash %rep making the pattern to be replaced (the first field, $F[0]) the key and the replacement ($F[1]) the value. * END{} : this is executed after the input file (replacements) has been read.

• open(A,"file") : open the file file for reading with filehandle A.

• while (<A>) : read the file line by line.

• s/// for keys(%rep) : this will iterate through all the keys of the %rep hash, saving each key as the special variable $_. The s/// is the substitution operator and is making the same substitution as explained in Michael's answer.

You could also read through the file and use sed as shown in the other answers:

$ sed 's/->/\t/' replacements | 
    while IFS=$'\t' read from to; do sed -i "s/\b$from\b/$to/g" file; done