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Hi would like extract N number of lines after matching the first incidence of a string printing the N lines following using awk. The string is repeated a number of times in the file I am processing . I have tried using this command:

'c&&c--;/XCHT/{c=10}'

This prints all incidences of the match + 10 lines. I have seen various versions of this command after extensive searches but all versions produce largely the same result as below. I have looked around to find . I would like some tips on how to modify this command to achieve the result

The result of the match I would like to achieve is as follows

| XCHT            |    |
|-----------------|----|
| 柴胡chaihu      | 24 |
| 黄芩huangqin    | 9  |
| 法半夏banxia    | 12 |
| 生姜shengjiang  | 9  |
| 刺五加ciwujia   | 9  |
| 大枣dazao       | 6  |
| 炙甘草zhigancao | 9  |
|                 |    |
|                 |    |

A section of the file looks like this:

## XCHT
| XCHT            |    |
|-----------------|----|
| 柴胡chaihu      | 24 |
| 黄芩huangqin    | 9  |
| 法半夏banxia    | 12 |
| 生姜shengjiang  | 9  |
| 刺五加ciwujia   | 9  |
| 大枣dazao       | 6  |
| 炙甘草zhigancao | 9  |
|                 |    |
|                 |    |


## XCHT+CM

|                 |    |
|-----------------|----|
| 柴胡chaihu      | 24 |
| 黄芩huangqin    | 9  |
| 法半夏banxia    | 12 |
| 干姜ganjiang    | 9  |
| 五味子wuweizi   | 9  |
| 炙甘草zhigancao | 9  |
|                 |    |
|                 |    |

## XCHT+TM


| XCHT+TM                 |    |
|-----------------        |----|
| 柴胡chaihu              | 24 |
| 黄芩huangqin            | 9  |
| 法天花粉tianhuafen      | 12 |
| 生姜shengjiang          | 9  |
| 刺五加ciwujia           | 12 |
| 大枣dazao               | 6  |
| 炙甘草zhigancao         | 9  |
|                         |    |
|                         |    |
 

| XCHT-HQin+FL    |    |
|-----------------|----|
| 柴胡chaihu      | 24 |
| 黄茯苓fuling    | 12 |
| 法半夏banxia    | 12 |
| 生姜shengjiang  | 9  |
| 刺五加ciwujia   | 9  |
| 大枣dazao       | 6  |
| 炙甘草zhigancao | 9  |
|                 |    |
|                 |    |
## XCHT-DZ+ML

| XCHT-DZ+ML      |     |
|-----------------|-----|
| 柴胡chaihu      | 12  |
| 黄芩huangqin    | 4.5 |
| 法半夏banxia    | 6   |
| 生姜shengjiang  | 4.5 |
| 刺五加ciwujia   | 4.5 |
| 牡蛎 muli       | 6   |
| 炙甘草zhigancao | 4.5 |
|                 |     |
|                 |     |

The result of the command 'c&&c--;/XCHT/{c=10}' on the file

| XCHT            |    |
|-----------------|----|
| 柴胡chaihu      | 24 |
| 黄芩huangqin    | 9  |
| 法半夏banxia    | 12 |
| 生姜shengjiang  | 9  |
| 刺五加ciwujia   | 9  |
| 大枣dazao       | 6  |
| 炙甘草zhigancao | 9  |
|                 |    |
|                 |    |

| XCHT            |    |
|-----------------|----|
| 柴胡chaihu      | 24 |
| 黄芩huangqin    | 9  |
| 法半夏banxia    | 12 |
| 干姜ganjiang    | 9  |
| 五味子wuweizi   | 9  |
| 炙甘草zhigancao | 9  |
|                 |    |
|                 |    |



| XCHT+TM                 |    |
|-----------------        |----|
| 柴胡chaihu              | 24 |
| 黄芩huangqin            | 9  |
| 法天花粉tianhuafen      | 12 |
| 生姜shengjiang          | 9  |
| 刺五加ciwujia           | 12 |
| 大枣dazao               | 6  |
| 炙甘草zhigancao         | 9  |
|                         |    |
|                         |    |

| XCHT-DZ+ML      |     |
|-----------------|-----|
| 柴胡chaihu      | 12  |
| 黄芩huangqin    | 4.5 |
| 法半夏banxia    | 6   |
| 生姜shengjiang  | 4.5 |
| 刺五加ciwujia   | 4.5 |
| 牡蛎 muli       | 6   |
| 炙甘草zhigancao | 4.5 |
|                 |     |
|                 |     |

| Xiao Chaihi Tang -HQ+BS |    |
|-------------------------|----|
| 柴胡chaihu              | 24 |
| 白芍baishao             | 9  |
| 法半夏banxia            | 12 |
| 生姜shengjiang          | 9  |
| 刺五加ciwujia           | 9  |
| 大枣dazao               | 6  |
| 炙甘草zhigancao         | 9

The tables are a bit wonky as a result of copying them to the webpage. Any help of advice will be much appreciated .

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4
  • Are the | part of the file or did you add them here only? Commented Feb 1, 2022 at 10:50
  • And does it need to be awk? If you have GNU grep you could just do grep -m1 -A10 XCHT. Commented Feb 1, 2022 at 10:53
  • the | are part of the file used as table separators Commented Feb 1, 2022 at 20:57
  • Are those lines starting with ## really present above some blocks in your input, sometimes with a blank line after them, other times not? Commented Feb 1, 2022 at 22:05

2 Answers 2

Reset to default
6

One way to handle this is to exit when c goes back to 0:

c { print; if (--c == 0) exit }; /XCHT/{c=10}

or more concisely,

c; c && !--c { exit }; /XCHT/{c=10}

GNU grep can do something similar:

grep -m1 -A10 XCHT

(but this will show the first line matching “XCHT” as well).

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4
  • Thanks Stephen that did the trick . I had an idea that it might be something to do with exit but had no idea where to put it . I admit I only vaguely understand the use of c in an awk program . Do you have any tips for understanding it' usage, It does not seem to be well documented in any of the books or web resources I've come across. Commented Feb 1, 2022 at 21:34
  • 1
    @ajr_chm c is just a variable, it could be named count or fluffy_bunny or anything else but c is a pretty common name for a counter variable. See printing-with-sed-or-awk-a-line-following-a-matching-pattern for more info on this and other awk idioms. Commented Feb 1, 2022 at 22:35
  • Why is the c; present in the beginning of this command but not in any of the commands in the link . Something to do with the presence of exit ? Commented Feb 2, 2022 at 7:10
  • 1
    @ajr_chm yes; in the linked examples, the conditions determine whether to print, but here there is one condition to print (c), and another to exit. c; is equivalent to c { print };, or more explicitly { if (c != 0) print }; (treating c as a purely numeric variable). Commented Feb 2, 2022 at 8:07
0

You seem to be trying to print a blank-line-separated record that just happens to be 10 lines long. Instead of counting lines and hard-coding how many lines you think are in a record, with awk you can just set RS to a null string to simply deal with such records no matter their length.

If those lines starting with ## aren't really present in your input then all you need is:

awk -v RS= '/XCHT/{print; exit}' file

otherwise if those lines really are present then we can remove them with a sub():

$ awk -v RS= '{sub(/##[^\n]*(\n|$)/,"")} /XCHT/{print; exit}' file
| XCHT            |    |
|-----------------|----|
| 柴胡chaihu      | 24 |
| 黄芩huangqin    | 9  |
| 法半夏banxia    | 12 |
| 生姜shengjiang  | 9  |
| 刺五加ciwujia   | 9  |
| 大枣dazao       | 6  |
| 炙甘草zhigancao | 9  |
|                 |    |
|                 |    |
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