If you are in the middle of a text processing pipeline, and need to insert a shell or environment variable into the output of awk, you can use the “-v” flag.
Here are two files containing animal classifications:
$ echo -e "shark=fish\ndolphin=mammal" > ocean.txt $ echo -e "dog=mammal\neagle=bird" > land.txt
By passing the loop variable in using “-v”, it can be used in the awk output.
$ for tfile in ocean land; do cat $tfile.txt | awk -v tfile=$tfile -F'=' '{ printf("A %s is a %s and lives in %s\n",$1,$2,tfile) }'; done
A shark is a fish and lives in ocean
A dolphin is a mammal and lives in ocean
A dog is a mammal and lives in land
A eagle is a bird and lives in land
This can be used for any shell or environment variable.
REFERENCES
cyberciti, passing shell variables to awk
tecnmint, using awk with BEGIN and END
NOTES
another example of using outside variable inside awk printf
thedir="/tmp"
ls $thedir | awk -v thedir=$thedir '{ printf "directory %s has file %s\n",thedir,$1 }'