LinuxQuestions.org - [SOLVED] help understanding awk

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help understanding awk

I am trying to debug a script that another person wrote. I am not very strong understanding awk. Can somebody please explain what this line is doing?

cat ${origfile} | awk '{sub("\014","\n\\page\n");print $0 "\par"}' >>${rtftempfile}

I know awk is doing some kind of manipulation of the acsii file ${origfile}, just not sure what.

Thanks

The syntax of the sub function is:

Code:

sub(regexp, replacement [, target])

where regexp is the regular expression to match and replacement is the string that substitutes the matching pattern. The target is optional: if not specified the whole record $0 is used. In practice your statement:

Code:

sub("\014","\n\\page\n")

should substitute every occurrence of the character whose octal code is 014 (form feed in the ASCII table) with a newline, followed by \page and again a newline. Take in mind that in awk regexps, the \NNN is an escape sequence to match ascii characters by means of their octal value. Hope this helps.

Google "gawk". There is book in postscript format about gawk ("gnu awk"). Awk is almost a programming language - so do not expect reasonably introduction in the two or three posts.

What does the "\par" represent after the record $0?

It is a string with those characters in it.

Quote:

Originally Posted by bino25 (Post 4430556)

What does the "\par" represent after the record $0?

Literally "par". The backslash is treated as an escape character (quite not useful here) so that \p is treated as p. If you want to print out a literal "\par" you have to escape the escape character:

Code:

print $0 "\\par"

Regarding the synatx of the print command, you can print out multiple strings (in this case $0 followed by "par"). Just take in mind that if you separate them with a comma, they will be printed out separated by the OFS (Output Field Separator, a blank space by default). If you omit the commas, they will be concatenated together. Example:

Code:

$ cat > file

line1

line2

$ awk '{print $0 "\par"}' file

awk: warning: escape sequence `\p' treated as plain `p'

line1par

line2par

$ awk '{print $0, "\par"}' file

awk: warning: escape sequence `\p' treated as plain `p'

line1 par

line2 par

Hope this helps. If you want to learn more about awk, here are two useful links:
http://www.grymoire.com/Unix/Awk.html
http://www.gnu.org/software/gawk/manual/

You guys rock!!! Thanks for all of the help!!