Open main menu
Home
Random
Recent changes
Special pages
Community portal
Preferences
About Wikipedia
Disclaimers
Incubator escapee wiki
Search
User menu
Talk
Dark mode
Contributions
Create account
Log in
Editing
AWK
(section)
Warning:
You are not logged in. Your IP address will be publicly visible if you make any edits. If you
log in
or
create an account
, your edits will be attributed to your username, along with other benefits.
Anti-spam check. Do
not
fill this in!
=== Match a range of input lines === <syntaxhighlight lang="awk"> NR % 4 == 1, NR % 4 == 3 { printf "%6d %s\n", NR, $0 } </syntaxhighlight> The action statement prints each line numbered. The printf function emulates the standard C [[printf]] and works similarly to the print command described above. The pattern to match, however, works as follows: ''NR'' is the number of records, typically lines of input, AWK has so far read, i.e. the current line number, starting at 1 for the first line of input. ''%'' is the [[modulo operation|modulo]] operator. ''NR % 4 == 1'' is true for the 1st, 5th, 9th, etc., lines of input. Likewise, ''NR % 4 == 3'' is true for the 3rd, 7th, 11th, etc., lines of input. The range pattern is false until the first part matches, on line 1, and then remains true up to and including when the second part matches, on line 3. It then stays false until the first part matches again on line 5. Thus, the program prints lines 1,2,3, skips line 4, and then 5,6,7, and so on. For each line, it prints the line number (on a 6 character-wide field) and then the line contents. For example, when executed on this input: Rome Florence Milan Naples Turin Venice The previous program prints: 1 Rome 2 Florence 3 Milan 5 Turin 6 Venice ==== Printing the initial or the final part of a file ==== As a special case, when the first part of a range pattern is constantly true, e.g. ''1'', the range will start at the beginning of the input. Similarly, if the second part is constantly false, e.g. ''0'', the range will continue until the end of input. For example, <syntaxhighlight lang="awk"> /^--cut here--$/, 0 </syntaxhighlight> prints lines of input from the first line matching the regular expression ''^--cut here--$'', that is, a line containing only the phrase "--cut here--", to the end.
Edit summary
(Briefly describe your changes)
By publishing changes, you agree to the
Terms of Use
, and you irrevocably agree to release your contribution under the
CC BY-SA 4.0 License
and the
GFDL
. You agree that a hyperlink or URL is sufficient attribution under the Creative Commons license.
Cancel
Editing help
(opens in new window)