Awk

• in 1970’s
• Scripting languague to do quick and dirty tasks like counting and reporting from files.
• awk is superset of grep
  • shorter and better than writing python script
• Interpreted Language

Timeline | History of awk development :========|============================================================== 1969 | ED (editor) Ken Thompson, sucessor of QED 1973 | Pipe | command, Thompson liberated grep from ED regex library 1973 | YACC spurs the tradition of creating new little languages 1974 | created sed 1975 | LEX 1977 | Using LEX and YACC, wrote grammer for awk 1985 | New AWK with user defined functions. Maintained by Brian Kernighan 1991 | POSIX was standardised

• Generate body of html pages (image gallery) from awk
• Regex match, filter on column values
• PERL is heavily influenced by awk

“MS-DOS was a pretty pathetic operating system” Microsoft has left the chat

• A lovestory

AWK is a domain-specific language designed for text processing and typically used as a data extraction and reporting tool

1. Variable which defines values which can be changed such as field separator and record separator.
2. Variable which can be used for processing and reports such as Number of records, number of fields.
3. pattern scanning and processing language

awk 'BEGIN{RS="\n";FS=","; \
        print"@ Additions,Deletions"} { \
        if($2=="")print$1" 0,0,0"; \
        else if($3=="")print$0",0"; \
        else print$0}'

Structure

BEGINE {}
CONDITIONS {ACTION1}
           {ACTION2}
END {}

Tasks we can accomplish with awk scripting

1. Report only on required info like IP addr from ip a output
2. Print output in tabular format

1. printf instead of print
2. left alignment
3. column seperator (optional)
4. Next line - important