grep and sed command

i have a truckload of files with sql commands in them, i have been asked to extract all database table names from the files How can I use grep and sed to parse t开发者_JAVA技巧he files and create a list of the unique table names in a text file ..one per line?

the name names all seem to start with "db_" which is handy!

what would be the best way to use grep and sed together to pull the table names out?

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This will search for lines containing the table names. The output of this will quickly reveal if a more selective search is needed:

grep "\<db_[a-zA-Z0-9_]*" *.sql

Once the proper search is sorted out, remove all other characters from lines with tablenames:

grep "\<db_[a-zA-Z0-9_]*" *.sql  |  sed 's/.*\(\<db_[a-zA-Z0-9_]*\).*/\1/'

Once that's running, add on a sort and remove duplicates:

(same last pipe expression)  |  sort  |  uniq

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you just need grep

grep -owE "db_[a-zA-Z0-9]+" file|sort -u

or awk

awk '{for(i=1;i<=NF;i++)if($i~/^db_[a-zA-Z0-9]+/){print $i} }' file