Ggtcf

How much theory knowledge is actually used while playing?

How to convince somebody that he is fit for something else, but not this job?

Why do ¬, ∀ and ∃ have the same precedence?

Is there a nicer/politer/more positive alternative for "negates"?

"It doesn't matter" or "it won't matter"?

What kind of floor tile is this?

Giving feedback to someone without sounding prejudiced

Does the reader need to like the PoV character?

What are some good ways to treat frozen vegetables such that they behave like fresh vegetables when stir frying them?

How do I tell my boss that I'm quitting soon, especially given that a colleague just left this week

Doesn't the system of the Supreme Court oppose justice?

PTIJ: Why is Haman obsessed with Bose?

Which was the first story featuring espers?

Do we have to expect a queue for the shuttle from Watford Junction to Harry Potter Studio?

The IT department bottlenecks progress, how should I handle this?

What fields between the rationals and the reals allow a good notion of 2D distance?

Change the color of a single dot in `ddot` symbol

How would you translate "more" for use as an interface button?

What features enable the Su-25 Frogfoot to operate with such a wide variety of fuels?

Is my low blitz game drawing rate at www.chess.com an indicator that I am weak in chess?

What's the name of the logical fallacy where a debater extends a statement far beyond the original statement to make it true?

Does the Linux kernel need a file system to run?

Why does this expression simplify as such?

What does Apple's new App Store requirement mean

Merge 2nd line of txt files together

How do I parse command line arguments in Bash?How do I tell if a regular file does not exist in Bash?How to count all the lines of code in a directory recursively?Linux: Merging multiple files, each on a new lineHow to merge two files line by line in BashHow to set a variable to the output of a command in Bash?Concatenate multiple files but include filename as section headersHow to merge every two lines into one from the command line?Read a file line by line assigning the value to a variableMerge two files using awk in linux

1

1

I have a few hundred txt files with 2 lines each.

To merge them, I would generally do:

cat *.txt > final.txt

however, I only need to do that for 2nd line of each file so the final output is like

2nd line of 1st file
2nd line of 2nd file
2nd line of 3rd file
(and so on..)

Any ideas how I can accomplish this?

bash awk cat

share|improve this question

edited Mar 7 at 23:47

RavinderSingh13

30.2k41639

asked Mar 7 at 19:06

Allison64Allison64

82

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  awk 'NR==2' file will print the 2nd line of the file
  
  – PS.
  Mar 7 at 19:09
  

  
  
  
  

add a comment | 

1

1

I have a few hundred txt files with 2 lines each.

To merge them, I would generally do:

cat *.txt > final.txt

however, I only need to do that for 2nd line of each file so the final output is like

2nd line of 1st file
2nd line of 2nd file
2nd line of 3rd file
(and so on..)

Any ideas how I can accomplish this?

bash awk cat

share|improve this question

edited Mar 7 at 23:47

RavinderSingh13

30.2k41639

asked Mar 7 at 19:06

Allison64Allison64

82

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  awk 'NR==2' file will print the 2nd line of the file
  
  – PS.
  Mar 7 at 19:09
  

  
  
  
  

add a comment | 

I have a few hundred txt files with 2 lines each.

To merge them, I would generally do:

cat *.txt > final.txt

however, I only need to do that for 2nd line of each file so the final output is like

2nd line of 1st file
2nd line of 2nd file
2nd line of 3rd file
(and so on..)

Any ideas how I can accomplish this?

bash awk cat

share|improve this question

edited Mar 7 at 23:47

RavinderSingh13

30.2k41639

asked Mar 7 at 19:06

Allison64Allison64

82

cat *.txt > final.txt

2nd line of 1st file
2nd line of 2nd file
2nd line of 3rd file
(and so on..)

share|improve this question

edited Mar 7 at 23:47

RavinderSingh13

30.2k41639

asked Mar 7 at 19:06

Allison64Allison64

82

share|improve this question

edited Mar 7 at 23:47

RavinderSingh13

30.2k41639

asked Mar 7 at 19:06

Allison64Allison64

82

edited Mar 7 at 23:47

RavinderSingh13

30.2k41639

edited Mar 7 at 23:47

RavinderSingh13

30.2k41639

asked Mar 7 at 19:06

Allison64Allison64

82

asked Mar 7 at 19:06

Allison64Allison64

82

5 Answers
5

active

oldest

votes

1

1st solution: Could you please try following with GNU awk. nextfile is very nice option in GNU awk which will skip all lines in current Input_file when a condition is MET.

awk 'FNR==2print;nextfile' *.txt > output_file

---

---

2nd solution: In case you don't have GNU awk try. Here since we are assuming there is NO nextfile in awk so I am creating a flag on each file's 2nd line and when it is TRUE simply going next line/skipping them and trying to save sometime. NOTE that this flag value will be RESET on each file's first line too.

awk 'FNR==1flag="" FNR==2print;flag=1 flagnext' *.txt > output_file

---

---

3rd solution: Adding while and find approach too here with head and tail. AFAIK head and tail shouldn't read whole file.

while read line
do
 head -n +2 "$line" | tail -1 
done < <(find -type f -name "*.txt") > "output_file"

share|improve this answer

edited Mar 7 at 19:39

answered Mar 7 at 19:14

RavinderSingh13RavinderSingh13

30.2k41639

add a comment | 

1

With GNU sed:

sed -n -s 2p *.txt > final.txt

or

sed -s '2!d' *.txt > final.txt

From man sed:

-s: consider files as separate rather than as a single continuous long stream.

share|improve this answer

edited Mar 7 at 19:25

answered Mar 7 at 19:23

CyrusCyrus

46.7k43880

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  -s added to notes :)
  
  – PS.
  Mar 7 at 19:24
  

  
  
  
  

add a comment | 

0

find . -name "*.txt" -type f -exec awk 'NR==2' ;

share|improve this answer

answered Mar 7 at 19:12

PS.PS.

7,577828

add a comment | 

0

Use awk

awk 'FNR == 2 print; nextfile ' *.txt > final.txt

FNR contains the line number within the current file. When it's on line 2, it will print the line and then go to the next file.

share|improve this answer

answered Mar 7 at 19:12

BarmarBarmar

433k36257359

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Hi Barmar sir, since you are an expert of bash would like to request you to please check my 3rd(while+find) answer if that will good in terms of speed etc, kindly provide your views on same.
  
  – RavinderSingh13
  Mar 7 at 19:29
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  It's acceptable, just very verbose and runs lots of processes.
  
  – Barmar
  Mar 7 at 19:31
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thank you for your view, appreciate it.
  
  – RavinderSingh13
  Mar 7 at 19:33
  

  
  
  
  

add a comment | 

0

Using Perl

 perl -ne ' if($.==2) print ; close(ARGV) ' *.txt

with sample files

$ cat allison1.txt
line1 in file1
line2 in file1

$ cat allison2.txt
line1 in file2
line2 in file2

$ cat allison3.txt
line1 in file3
line2 in file3

$ perl -ne ' if($.==2) print ; close(ARGV) ' allison*txt
line2 in file1
line2 in file2
line2 in file3

$

share|improve this answer

answered Mar 8 at 5:02

stack0114106stack0114106

4,7602423

add a comment | 

Your Answer

StackExchange.ifUsing("editor", function ()
StackExchange.using("externalEditor", function ()
StackExchange.using("snippets", function ()
StackExchange.snippets.init();
);
);
, "code-snippets");

StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "1"
;
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: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
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
);



);

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%2fstackoverflow.com%2fquestions%2f55051127%2fmerge-2nd-line-of-txt-files-together%23new-answer', 'question_page');

);

Post as a guest

Name

Email

Required, but never shown

1

1st solution: Could you please try following with GNU awk. nextfile is very nice option in GNU awk which will skip all lines in current Input_file when a condition is MET.

awk 'FNR==2print;nextfile' *.txt > output_file

---

---

2nd solution: In case you don't have GNU awk try. Here since we are assuming there is NO nextfile in awk so I am creating a flag on each file's 2nd line and when it is TRUE simply going next line/skipping them and trying to save sometime. NOTE that this flag value will be RESET on each file's first line too.

awk 'FNR==1flag="" FNR==2print;flag=1 flagnext' *.txt > output_file

---

---

3rd solution: Adding while and find approach too here with head and tail. AFAIK head and tail shouldn't read whole file.

while read line
do
 head -n +2 "$line" | tail -1 
done < <(find -type f -name "*.txt") > "output_file"

share|improve this answer

edited Mar 7 at 19:39

answered Mar 7 at 19:14

RavinderSingh13RavinderSingh13

30.2k41639

add a comment | 

1

1st solution: Could you please try following with GNU awk. nextfile is very nice option in GNU awk which will skip all lines in current Input_file when a condition is MET.

awk 'FNR==2print;nextfile' *.txt > output_file

---

---

2nd solution: In case you don't have GNU awk try. Here since we are assuming there is NO nextfile in awk so I am creating a flag on each file's 2nd line and when it is TRUE simply going next line/skipping them and trying to save sometime. NOTE that this flag value will be RESET on each file's first line too.

awk 'FNR==1flag="" FNR==2print;flag=1 flagnext' *.txt > output_file

---

---

3rd solution: Adding while and find approach too here with head and tail. AFAIK head and tail shouldn't read whole file.

while read line
do
 head -n +2 "$line" | tail -1 
done < <(find -type f -name "*.txt") > "output_file"

share|improve this answer

edited Mar 7 at 19:39

answered Mar 7 at 19:14

RavinderSingh13RavinderSingh13

30.2k41639

add a comment | 

1st solution: Could you please try following with GNU awk. nextfile is very nice option in GNU awk which will skip all lines in current Input_file when a condition is MET.

awk 'FNR==2print;nextfile' *.txt > output_file

---

---

2nd solution: In case you don't have GNU awk try. Here since we are assuming there is NO nextfile in awk so I am creating a flag on each file's 2nd line and when it is TRUE simply going next line/skipping them and trying to save sometime. NOTE that this flag value will be RESET on each file's first line too.

awk 'FNR==1flag="" FNR==2print;flag=1 flagnext' *.txt > output_file

---

---

3rd solution: Adding while and find approach too here with head and tail. AFAIK head and tail shouldn't read whole file.

while read line
do
 head -n +2 "$line" | tail -1 
done < <(find -type f -name "*.txt") > "output_file"

share|improve this answer

edited Mar 7 at 19:39

answered Mar 7 at 19:14

RavinderSingh13RavinderSingh13

30.2k41639

awk 'FNR==2print;nextfile' *.txt > output_file

awk 'FNR==1flag="" FNR==2print;flag=1 flagnext' *.txt > output_file

while read line
do
 head -n +2 "$line" | tail -1 
done < <(find -type f -name "*.txt") > "output_file"

share|improve this answer

edited Mar 7 at 19:39

answered Mar 7 at 19:14

RavinderSingh13RavinderSingh13

30.2k41639

answered Mar 7 at 19:14

RavinderSingh13RavinderSingh13

30.2k41639

answered Mar 7 at 19:14

RavinderSingh13RavinderSingh13

30.2k41639

1

With GNU sed:

sed -n -s 2p *.txt > final.txt

or

sed -s '2!d' *.txt > final.txt

From man sed:

-s: consider files as separate rather than as a single continuous long stream.

share|improve this answer

edited Mar 7 at 19:25

answered Mar 7 at 19:23

CyrusCyrus

46.7k43880

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  -s added to notes :)
  
  – PS.
  Mar 7 at 19:24
  

  
  
  
  

add a comment | 

1

With GNU sed:

sed -n -s 2p *.txt > final.txt

or

sed -s '2!d' *.txt > final.txt

From man sed:

-s: consider files as separate rather than as a single continuous long stream.

share|improve this answer

edited Mar 7 at 19:25

answered Mar 7 at 19:23

CyrusCyrus

46.7k43880

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  -s added to notes :)
  
  – PS.
  Mar 7 at 19:24
  

  
  
  
  

add a comment | 

With GNU sed:

sed -n -s 2p *.txt > final.txt

or

sed -s '2!d' *.txt > final.txt

From man sed:

-s: consider files as separate rather than as a single continuous long stream.

share|improve this answer

edited Mar 7 at 19:25

answered Mar 7 at 19:23

CyrusCyrus

46.7k43880

sed -n -s 2p *.txt > final.txt

sed -s '2!d' *.txt > final.txt

share|improve this answer

edited Mar 7 at 19:25

answered Mar 7 at 19:23

CyrusCyrus

46.7k43880

answered Mar 7 at 19:23

CyrusCyrus

46.7k43880

answered Mar 7 at 19:23

CyrusCyrus

46.7k43880

0

find . -name "*.txt" -type f -exec awk 'NR==2' ;

share|improve this answer

answered Mar 7 at 19:12

PS.PS.

7,577828

add a comment | 

0

find . -name "*.txt" -type f -exec awk 'NR==2' ;

share|improve this answer

answered Mar 7 at 19:12

PS.PS.

7,577828

add a comment | 

find . -name "*.txt" -type f -exec awk 'NR==2' ;

share|improve this answer

answered Mar 7 at 19:12

PS.PS.

7,577828

find . -name "*.txt" -type f -exec awk 'NR==2' ;

share|improve this answer

answered Mar 7 at 19:12

PS.PS.

7,577828

answered Mar 7 at 19:12

PS.PS.

7,577828

answered Mar 7 at 19:12

PS.PS.

7,577828

0

Use awk

awk 'FNR == 2 print; nextfile ' *.txt > final.txt

FNR contains the line number within the current file. When it's on line 2, it will print the line and then go to the next file.

share|improve this answer

answered Mar 7 at 19:12

BarmarBarmar

433k36257359

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Hi Barmar sir, since you are an expert of bash would like to request you to please check my 3rd(while+find) answer if that will good in terms of speed etc, kindly provide your views on same.
  
  – RavinderSingh13
  Mar 7 at 19:29
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  It's acceptable, just very verbose and runs lots of processes.
  
  – Barmar
  Mar 7 at 19:31
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thank you for your view, appreciate it.
  
  – RavinderSingh13
  Mar 7 at 19:33
  

  
  
  
  

add a comment | 

0

Use awk

awk 'FNR == 2 print; nextfile ' *.txt > final.txt

FNR contains the line number within the current file. When it's on line 2, it will print the line and then go to the next file.

share|improve this answer

answered Mar 7 at 19:12

BarmarBarmar

433k36257359

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Hi Barmar sir, since you are an expert of bash would like to request you to please check my 3rd(while+find) answer if that will good in terms of speed etc, kindly provide your views on same.
  
  – RavinderSingh13
  Mar 7 at 19:29
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  It's acceptable, just very verbose and runs lots of processes.
  
  – Barmar
  Mar 7 at 19:31
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thank you for your view, appreciate it.
  
  – RavinderSingh13
  Mar 7 at 19:33
  

  
  
  
  

add a comment | 

Use awk

awk 'FNR == 2 print; nextfile ' *.txt > final.txt

FNR contains the line number within the current file. When it's on line 2, it will print the line and then go to the next file.

share|improve this answer

answered Mar 7 at 19:12

BarmarBarmar

433k36257359

awk 'FNR == 2 print; nextfile ' *.txt > final.txt

share|improve this answer

answered Mar 7 at 19:12

BarmarBarmar

433k36257359

answered Mar 7 at 19:12

BarmarBarmar

433k36257359

answered Mar 7 at 19:12

BarmarBarmar

433k36257359

0

Using Perl

 perl -ne ' if($.==2) print ; close(ARGV) ' *.txt

with sample files

$ cat allison1.txt
line1 in file1
line2 in file1

$ cat allison2.txt
line1 in file2
line2 in file2

$ cat allison3.txt
line1 in file3
line2 in file3

$ perl -ne ' if($.==2) print ; close(ARGV) ' allison*txt
line2 in file1
line2 in file2
line2 in file3

$

share|improve this answer

answered Mar 8 at 5:02

stack0114106stack0114106

4,7602423

add a comment | 

0

Using Perl

 perl -ne ' if($.==2) print ; close(ARGV) ' *.txt

with sample files

$ cat allison1.txt
line1 in file1
line2 in file1

$ cat allison2.txt
line1 in file2
line2 in file2

$ cat allison3.txt
line1 in file3
line2 in file3

$ perl -ne ' if($.==2) print ; close(ARGV) ' allison*txt
line2 in file1
line2 in file2
line2 in file3

$

share|improve this answer

answered Mar 8 at 5:02

stack0114106stack0114106

4,7602423

add a comment | 

Using Perl

 perl -ne ' if($.==2) print ; close(ARGV) ' *.txt

with sample files

$ cat allison1.txt
line1 in file1
line2 in file1

$ cat allison2.txt
line1 in file2
line2 in file2

$ cat allison3.txt
line1 in file3
line2 in file3

$ perl -ne ' if($.==2) print ; close(ARGV) ' allison*txt
line2 in file1
line2 in file2
line2 in file3

$

share|improve this answer

answered Mar 8 at 5:02

stack0114106stack0114106

4,7602423

 perl -ne ' if($.==2) print ; close(ARGV) ' *.txt

$ cat allison1.txt
line1 in file1
line2 in file1

$ cat allison2.txt
line1 in file2
line2 in file2

$ cat allison3.txt
line1 in file3
line2 in file3

$ perl -ne ' if($.==2) print ; close(ARGV) ' allison*txt
line2 in file1
line2 in file2
line2 in file3

$

share|improve this answer

answered Mar 8 at 5:02

stack0114106stack0114106

4,7602423

answered Mar 8 at 5:02

stack0114106stack0114106

4,7602423

answered Mar 8 at 5:02

stack0114106stack0114106

4,7602423