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GAWK Find Pattern Print Lines Before and After

Using grep I can easily use:

Code:

cvs log |grep -iB 10 -A 10 'date: 2013-10-30'

to display search results and 10 lines before and after. How can this be accompished using gawk?

I can't really see why you would want to do it with awk, but

if countdown greater than 0
- print $0
- subtract 1 from countdown
- next record
if pattern exists
- print all elements in array
- print $0
- unset array
- start countdown at 10
- next record
if pattern not exist
- if No of elements in array = 10
  - for element in 1 to 9,
    - array[element-1]=array[element];
  - array[9]="$0"
  - next record
- add $0 to array
- next record

^^ untested ( as well as unwritten as awk )
it can be done, but I don't know why since grep -C10 will do the same with less effort

NOTE:, there is probably a much better way of doing it in awk than my above 'logic'

Quote:

Originally Posted by metallica1973 (Post 5056097)

Using grep I can easily use:

Code:

cvs log |grep -iB 10 -A 10 'date: 2013-10-30'

to display search results and 10 lines before and after. How can this be accomplished using gawk?

I changed the 10-line context to 3 lines for ease of testing.

With this InFile ...

Code:

line 01

date: 2013-10-30

line 03

line 04

line 05

line 06

line 07

line 09

line 10

line 11

date: 2013-10-30

line 13

line 14

line 15

line 16

line 17

line 18

line 19

date: 2013-10-30

line 21

line 22

line 23

date: 2013-10-30

line 25

date: 2013-10-30

line 27

line 28

line 29

line 30

line 31

line 32

line 33

date: 2013-10-30

... this gawk ...

Code:

gawk '{l[NR]=$0; if ($0~"date: 2013-10-30") {for (j=NR-3;j<=NR+2;j++) {a[j]=1}; a[j]=a[j]+99}}

  END{for (j=1;j<=NR;j++) {if (a[j]) print l[j]; if (a[j]>9) print "---" }}' $InFile >$OutFile

... produced this OutFile ...

Code:

line 01

date: 2013-10-30

line 03

line 04

line 05

---

line 09

line 10

line 11

date: 2013-10-30

line 13

line 14

line 15

---

line 17

line 18

line 19

date: 2013-10-30

line 21

line 22

line 23

date: 2013-10-30

line 25

date: 2013-10-30

line 27

line 28

line 29

---

line 31

line 32

line 33

date: 2013-10-30

Daniel B. Martin

thanks for the reply. You have left me speechless on how long it would take to use gawk instead of simply using grep.