Try this in the folder where your vcf files are: Code: grep -l ':+[89][0-9]\{7\}$' *.vcf | xargs sed -i '/:+[89][0-9]\{7\}$/s/\+/\+9/g' .
grep -l ':+[89][0-9]\{7\}$' *.vcf | xargs sed -i '/:+[89][0-9]\{7\}$/s/\+/\+9/g'
~/Exported contacts$ grep -l ':+[89][0-9]\{7\}$' *.vcf | xargs sed -i '/:+[89][0-9]\{7\}$/s/\+/\+9/g' sed: no input files
~/MyDocs/Exported contacts $ grep -l ':+[89][0-9]\{7\}$' *.vcf | xargs sed -i ' /:+[89][0-9]\{7\}$/s/\+/\+9/g' sed: -i requires an argument