Mdthbs

Symmetry in quantum mechanics

How can I add custom success page

What do the Banks children have against barley water?

Re-submission of rejected manuscript without informing co-authors

Add an angle to a sphere

Shall I use personal or official e-mail account when registering to external websites for work purpose?

Is it legal to have the "// (c) 2019 John Smith" header in all files when there are hundreds of contributors?

Landlord wants to switch my lease to a "Land contract" to "get back at the city"

How to deal with fear of taking dependencies

How could a lack of term limits lead to a "dictatorship?"

What does it exactly mean if a random variable follows a distribution

Does it makes sense to buy a new cycle to learn riding?

Is there a way to make member function NOT callable from constructor?

I see my dog run

What to wear for invited talk in Canada

Why is the design of haulage companies so “special”?

Manga about a female worker who got dragged into another world together with this high school girl and she was just told she's not needed anymore

Copycat chess is back

COUNT(*) or MAX(id) - which is faster?

Ideas for 3rd eye abilities

"My colleague's body is amazing"

Why is my log file so massive? 22gb. I am running log backups

Can the Produce Flame cantrip be used to grapple, or as an unarmed strike, in the right circumstances?

How to move the player while also allowing forces to affect it

Awk syntax, strange variable?

Compare the similar file and not similar files display below output in awk?Comparing two files using Unix and AwkComparing Files based on 5 fields using Awk and BashFinding out the common lines in two files using 4 fields using awk and UNIXMerging 2 files with based on field matchUsing awk to select column data from separate filesCompare two files with awkJoining two files matching two columns with mismatches and in each matching line, substitute second column from file 1 into 6th column in file 2compare two files and print matches - large filesawk manipulation of a file

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty{ margin-bottom:0;
}

1

I have this awk command:

awk -F, 'NR==FNR{_1[$1]++;next}_1[$1]' file1 file2

I actually almost know what the program is doing, but I don't know what _1 means. The intention is to compare two files, one has 1 field and the other has 4 fields.

Here's what I'm trying to do. I have these files, I need to know which numbers on file1 is in file 2 and then print the record of file 2.

file1

89611862

89613696

84126597

88690669

60147342

file2

84126597,12345300943529348333,2805058C30730000,28

88767631,12345712012010684248,2805058C30730002,28

83218719,12345712012012622594,2805058C30730006,28

89611862,12345712012010174449,2805058C30730014,28

85933710,12345712012007778032,2805058C3073001A,26

88690669,12345712012012060159,2805058C3073001E,28

60147342,12345712012011235922,2805058C30730030,28

89613696,12345712012008043980,2805058C3073003C,28

84783612,12345712012031117926,2805058C3073004C,28

awk -F, 'NR==FNR{arr[$1]++;next}arr[$1]' file1 file2

But it only prints the last found record:

60147342,12345712012011235922,2805058C30730030,28 

Thanks!

awk

share|improve this question

edited yesterday

Kusalananda♦

140k17261435

asked yesterday

Chila MendezChila Mendez

83

New contributor

Chila Mendez is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  take care with the line terminators; some lines from file1 may be terminated by cr/lf, windows-mode. Do you have the same problem if you replace -F, with -F'[,r]'?
  
  – mosvy
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You are absolutely right!! I change it and it works, and yes, I have that problem with the file1. Thanks!!
  
  – Chila Mendez
  yesterday
  

  
  
  
  

add a comment | 

1

I have this awk command:

awk -F, 'NR==FNR{_1[$1]++;next}_1[$1]' file1 file2

I actually almost know what the program is doing, but I don't know what _1 means. The intention is to compare two files, one has 1 field and the other has 4 fields.

Here's what I'm trying to do. I have these files, I need to know which numbers on file1 is in file 2 and then print the record of file 2.

file1

89611862

89613696

84126597

88690669

60147342

file2

84126597,12345300943529348333,2805058C30730000,28

88767631,12345712012010684248,2805058C30730002,28

83218719,12345712012012622594,2805058C30730006,28

89611862,12345712012010174449,2805058C30730014,28

85933710,12345712012007778032,2805058C3073001A,26

88690669,12345712012012060159,2805058C3073001E,28

60147342,12345712012011235922,2805058C30730030,28

89613696,12345712012008043980,2805058C3073003C,28

84783612,12345712012031117926,2805058C3073004C,28

awk -F, 'NR==FNR{arr[$1]++;next}arr[$1]' file1 file2

But it only prints the last found record:

60147342,12345712012011235922,2805058C30730030,28 

Thanks!

awk

share|improve this question

edited yesterday

Kusalananda♦

140k17261435

asked yesterday

Chila MendezChila Mendez

83

New contributor

Chila Mendez is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  take care with the line terminators; some lines from file1 may be terminated by cr/lf, windows-mode. Do you have the same problem if you replace -F, with -F'[,r]'?
  
  – mosvy
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You are absolutely right!! I change it and it works, and yes, I have that problem with the file1. Thanks!!
  
  – Chila Mendez
  yesterday
  

  
  
  
  

add a comment | 

I have this awk command:

awk -F, 'NR==FNR{_1[$1]++;next}_1[$1]' file1 file2

I actually almost know what the program is doing, but I don't know what _1 means. The intention is to compare two files, one has 1 field and the other has 4 fields.

Here's what I'm trying to do. I have these files, I need to know which numbers on file1 is in file 2 and then print the record of file 2.

file1

89611862

89613696

84126597

88690669

60147342

file2

84126597,12345300943529348333,2805058C30730000,28

88767631,12345712012010684248,2805058C30730002,28

83218719,12345712012012622594,2805058C30730006,28

89611862,12345712012010174449,2805058C30730014,28

85933710,12345712012007778032,2805058C3073001A,26

88690669,12345712012012060159,2805058C3073001E,28

60147342,12345712012011235922,2805058C30730030,28

89613696,12345712012008043980,2805058C3073003C,28

84783612,12345712012031117926,2805058C3073004C,28

awk -F, 'NR==FNR{arr[$1]++;next}arr[$1]' file1 file2

But it only prints the last found record:

60147342,12345712012011235922,2805058C30730030,28 

Thanks!

awk

share|improve this question

edited yesterday

Kusalananda♦

140k17261435

asked yesterday

Chila MendezChila Mendez

83

New contributor

Chila Mendez is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

awk -F, 'NR==FNR{_1[$1]++;next}_1[$1]' file1 file2

89611862

89613696

84126597

88690669

60147342

84126597,12345300943529348333,2805058C30730000,28

88767631,12345712012010684248,2805058C30730002,28

83218719,12345712012012622594,2805058C30730006,28

89611862,12345712012010174449,2805058C30730014,28

85933710,12345712012007778032,2805058C3073001A,26

88690669,12345712012012060159,2805058C3073001E,28

60147342,12345712012011235922,2805058C30730030,28

89613696,12345712012008043980,2805058C3073003C,28

84783612,12345712012031117926,2805058C3073004C,28

awk -F, 'NR==FNR{arr[$1]++;next}arr[$1]' file1 file2

60147342,12345712012011235922,2805058C30730030,28 

share|improve this question

edited yesterday

Kusalananda♦

140k17261435

asked yesterday

Chila MendezChila Mendez

83

New contributor

Chila Mendez is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited yesterday

Kusalananda♦

140k17261435

asked yesterday

Chila MendezChila Mendez

83

New contributor

Chila Mendez is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

edited yesterday

Kusalananda♦

140k17261435

edited yesterday

Kusalananda♦

140k17261435

asked yesterday

Chila MendezChila Mendez

83

New contributor

Chila Mendez is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked yesterday

Chila MendezChila Mendez

83

1 Answer
1

active

oldest

votes

2

awk does not allow digit-only variable names (and variable names can't begin with a digit as well), so _1 is a trick to prepend _ in front of 1; so, _1 is a variable name in your awk program, which happens to be an array in this case.

Here is an example:

% awk 'BEGIN {1 = 3}'

awk: cmd. line:1: BEGIN {1 = 3}

awk: cmd. line:1:          ^ syntax error



% awk 'BEGIN {_1 = 3}'  # runs fine

---

As an aside, you should use readable variable names in your program to have better maintainability unless you're golfing intentionally.

share|improve this answer

answered yesterday

heemaylheemayl

36.2k378108

add a comment | 

Your Answer

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "106"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});

Chila Mendez is a new contributor. Be nice, and check out our Code of Conduct.

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Sign up using Google

Sign up using Facebook

Sign up using Email and Password

Post as a guest

Name

Email

Required, but never shown

StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f511093%2fawk-syntax-strange-variable%23new-answer', 'question_page');
}
);

Post as a guest

Name

Email

Required, but never shown

2

awk does not allow digit-only variable names (and variable names can't begin with a digit as well), so _1 is a trick to prepend _ in front of 1; so, _1 is a variable name in your awk program, which happens to be an array in this case.

Here is an example:

% awk 'BEGIN {1 = 3}'

awk: cmd. line:1: BEGIN {1 = 3}

awk: cmd. line:1:          ^ syntax error



% awk 'BEGIN {_1 = 3}'  # runs fine

---

As an aside, you should use readable variable names in your program to have better maintainability unless you're golfing intentionally.

share|improve this answer

answered yesterday

heemaylheemayl

36.2k378108

add a comment | 

2

awk does not allow digit-only variable names (and variable names can't begin with a digit as well), so _1 is a trick to prepend _ in front of 1; so, _1 is a variable name in your awk program, which happens to be an array in this case.

Here is an example:

% awk 'BEGIN {1 = 3}'

awk: cmd. line:1: BEGIN {1 = 3}

awk: cmd. line:1:          ^ syntax error



% awk 'BEGIN {_1 = 3}'  # runs fine

---

As an aside, you should use readable variable names in your program to have better maintainability unless you're golfing intentionally.

share|improve this answer

answered yesterday

heemaylheemayl

36.2k378108

add a comment | 

awk does not allow digit-only variable names (and variable names can't begin with a digit as well), so _1 is a trick to prepend _ in front of 1; so, _1 is a variable name in your awk program, which happens to be an array in this case.

Here is an example:

% awk 'BEGIN {1 = 3}'

awk: cmd. line:1: BEGIN {1 = 3}

awk: cmd. line:1:          ^ syntax error



% awk 'BEGIN {_1 = 3}'  # runs fine

---

As an aside, you should use readable variable names in your program to have better maintainability unless you're golfing intentionally.

share|improve this answer

answered yesterday

heemaylheemayl

36.2k378108

% awk 'BEGIN {1 = 3}'

awk: cmd. line:1: BEGIN {1 = 3}

awk: cmd. line:1:          ^ syntax error



% awk 'BEGIN {_1 = 3}'  # runs fine

share|improve this answer

answered yesterday

heemaylheemayl

36.2k378108

answered yesterday

heemaylheemayl

36.2k378108

answered yesterday

heemaylheemayl

36.2k378108