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How can I modify a line which contains 2nd occurence of a string?

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2

This post explains how to add a line at the beginning of a file from the terminal. But how do I modify from the terminal a line somewhere in a file if I do not know which line it is?

I should modify the line eni=10.*10**9 to eni=10.*10**8 note the exponents. It is the second time that eni appears

command-line

share|improve this question

edited 7 hours ago

Kulfy

7,5901010 gold badges3131 silver badges5858 bronze badges

asked 8 hours ago

mattiav27mattiav27

18711 gold badge11 silver badge99 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Do you mean the exact middle of a file?
  
  – guillermo chamorro
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  No I mean somewhere in the file
  
  – mattiav27
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  If not line number is there any pattern or some kind of phrase which is to be followed? Like add this line before a line which contains "blabla".
  
  – Kulfy
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Kulfy it is the second time the term 'eni' appears if that can be useful
  
  – mattiav27
  8 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  What exactly kind of modifications do you want? Please edit your question and try to make it more descriptive and specific.
  
  – Kulfy
  8 hours ago
  
  

  
  
  
  

 | 
show 1 more comment

2

This post explains how to add a line at the beginning of a file from the terminal. But how do I modify from the terminal a line somewhere in a file if I do not know which line it is?

I should modify the line eni=10.*10**9 to eni=10.*10**8 note the exponents. It is the second time that eni appears

command-line

share|improve this question

edited 7 hours ago

Kulfy

7,5901010 gold badges3131 silver badges5858 bronze badges

asked 8 hours ago

mattiav27mattiav27

18711 gold badge11 silver badge99 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Do you mean the exact middle of a file?
  
  – guillermo chamorro
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  No I mean somewhere in the file
  
  – mattiav27
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  If not line number is there any pattern or some kind of phrase which is to be followed? Like add this line before a line which contains "blabla".
  
  – Kulfy
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Kulfy it is the second time the term 'eni' appears if that can be useful
  
  – mattiav27
  8 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  What exactly kind of modifications do you want? Please edit your question and try to make it more descriptive and specific.
  
  – Kulfy
  8 hours ago
  
  

  
  
  
  

 | 
show 1 more comment

This post explains how to add a line at the beginning of a file from the terminal. But how do I modify from the terminal a line somewhere in a file if I do not know which line it is?

I should modify the line eni=10.*10**9 to eni=10.*10**8 note the exponents. It is the second time that eni appears

command-line

share|improve this question

edited 7 hours ago

Kulfy

7,5901010 gold badges3131 silver badges5858 bronze badges

asked 8 hours ago

mattiav27mattiav27

18711 gold badge11 silver badge99 bronze badges

share|improve this question

edited 7 hours ago

Kulfy

7,5901010 gold badges3131 silver badges5858 bronze badges

asked 8 hours ago

mattiav27mattiav27

18711 gold badge11 silver badge99 bronze badges

share|improve this question

edited 7 hours ago

Kulfy

7,5901010 gold badges3131 silver badges5858 bronze badges

asked 8 hours ago

mattiav27mattiav27

18711 gold badge11 silver badge99 bronze badges

edited 7 hours ago

Kulfy

7,5901010 gold badges3131 silver badges5858 bronze badges

edited 7 hours ago

Kulfy

7,5901010 gold badges3131 silver badges5858 bronze badges

asked 8 hours ago

mattiav27mattiav27

18711 gold badge11 silver badge99 bronze badges

asked 8 hours ago

mattiav27mattiav27

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3 Answers
3

active

oldest

votes

2

I think this is what you want:

line=$(grep -n -m2 "eni" file | tail -n1 | cut -f1 -d:)

sed -i $line's/9$/8/' file

share|improve this answer

edited 7 hours ago

answered 8 hours ago

guillermo chamorroguillermo chamorro

66111 silver badge1313 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @wjandrea modified the answer, take a look.
  
  – guillermo chamorro
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  Nice! You could simplify getting the line number: line="$(awk '/eni/ count+=1;if(count==2)print NR' test.txt)"
  
  – wjandrea
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This answer will match the second occurrence of eni and return the line number. Then it will change the last occurrence of 9 with 8 in that line. If more than one 9 are present in the same line, it will only change the last one and might miss the intended one.
  
  – Raffa
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @Raffa Yes, a more elaborate regex could be done, but OP's data doesn't show more text after the line, that's why I chose to simplify it to match what OP shows as a line. Note that OP wrote "I should modify the line", not x content in the line.
  
  – guillermo chamorro
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @guillermochamorro You did a good job, but I however recommend you add such explanation to your answer as it could prevent unintended modification to the file. Thank you
  
  – Raffa
  5 hours ago
  

  
  
  
  

add a comment | 

1

Using sed:

sed -i ': 1 ; N ; $!b1 ; s/eni=10.*10**9/eni=10.*10**8/2' filename

/ is one of the delimiters and is the escape character. is used so that bash won't interpret special characters as some command, like * as wildcard.

share|improve this answer

edited 7 hours ago

answered 7 hours ago

KulfyKulfy

7,5901010 gold badges3131 silver badges5858 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This answer will match the second occurrence of eni=10.*10**9 in a new line and will change it with eni=10.*10**8. Run it only once.
  
  – Raffa
  6 hours ago
  

  
  
  
  

add a comment | 

0

Since Ubuntu now ships with GNU Awk v4.0+ (which provides an inplace module) you could do something like

gawk -i inplace '/eni=/ if (++c == 2) sub(/10**9/,"10**8") 1' file

You can make the regular expressions /eni=/ and/or /10**9/ more or less specific as required.

share|improve this answer

answered 3 hours ago

steeldriversteeldriver

78.4k1212 gold badges129129 silver badges213213 bronze badges

add a comment | 

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2

I think this is what you want:

line=$(grep -n -m2 "eni" file | tail -n1 | cut -f1 -d:)

sed -i $line's/9$/8/' file

share|improve this answer

edited 7 hours ago

answered 8 hours ago

guillermo chamorroguillermo chamorro

66111 silver badge1313 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @wjandrea modified the answer, take a look.
  
  – guillermo chamorro
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  Nice! You could simplify getting the line number: line="$(awk '/eni/ count+=1;if(count==2)print NR' test.txt)"
  
  – wjandrea
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This answer will match the second occurrence of eni and return the line number. Then it will change the last occurrence of 9 with 8 in that line. If more than one 9 are present in the same line, it will only change the last one and might miss the intended one.
  
  – Raffa
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @Raffa Yes, a more elaborate regex could be done, but OP's data doesn't show more text after the line, that's why I chose to simplify it to match what OP shows as a line. Note that OP wrote "I should modify the line", not x content in the line.
  
  – guillermo chamorro
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @guillermochamorro You did a good job, but I however recommend you add such explanation to your answer as it could prevent unintended modification to the file. Thank you
  
  – Raffa
  5 hours ago
  

  
  
  
  

add a comment | 

2

I think this is what you want:

line=$(grep -n -m2 "eni" file | tail -n1 | cut -f1 -d:)

sed -i $line's/9$/8/' file

share|improve this answer

edited 7 hours ago

answered 8 hours ago

guillermo chamorroguillermo chamorro

66111 silver badge1313 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @wjandrea modified the answer, take a look.
  
  – guillermo chamorro
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  Nice! You could simplify getting the line number: line="$(awk '/eni/ count+=1;if(count==2)print NR' test.txt)"
  
  – wjandrea
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This answer will match the second occurrence of eni and return the line number. Then it will change the last occurrence of 9 with 8 in that line. If more than one 9 are present in the same line, it will only change the last one and might miss the intended one.
  
  – Raffa
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @Raffa Yes, a more elaborate regex could be done, but OP's data doesn't show more text after the line, that's why I chose to simplify it to match what OP shows as a line. Note that OP wrote "I should modify the line", not x content in the line.
  
  – guillermo chamorro
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @guillermochamorro You did a good job, but I however recommend you add such explanation to your answer as it could prevent unintended modification to the file. Thank you
  
  – Raffa
  5 hours ago
  

  
  
  
  

add a comment | 

I think this is what you want:

line=$(grep -n -m2 "eni" file | tail -n1 | cut -f1 -d:)

sed -i $line's/9$/8/' file

share|improve this answer

edited 7 hours ago

answered 8 hours ago

guillermo chamorroguillermo chamorro

66111 silver badge1313 bronze badges

line=$(grep -n -m2 "eni" file | tail -n1 | cut -f1 -d:)

sed -i $line's/9$/8/' file

share|improve this answer

edited 7 hours ago

answered 8 hours ago

guillermo chamorroguillermo chamorro

66111 silver badge1313 bronze badges

answered 8 hours ago

guillermo chamorroguillermo chamorro

66111 silver badge1313 bronze badges

answered 8 hours ago

guillermo chamorroguillermo chamorro

66111 silver badge1313 bronze badges

1

Using sed:

sed -i ': 1 ; N ; $!b1 ; s/eni=10.*10**9/eni=10.*10**8/2' filename

/ is one of the delimiters and is the escape character. is used so that bash won't interpret special characters as some command, like * as wildcard.

share|improve this answer

edited 7 hours ago

answered 7 hours ago

KulfyKulfy

7,5901010 gold badges3131 silver badges5858 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This answer will match the second occurrence of eni=10.*10**9 in a new line and will change it with eni=10.*10**8. Run it only once.
  
  – Raffa
  6 hours ago
  

  
  
  
  

add a comment | 

1

Using sed:

sed -i ': 1 ; N ; $!b1 ; s/eni=10.*10**9/eni=10.*10**8/2' filename

/ is one of the delimiters and is the escape character. is used so that bash won't interpret special characters as some command, like * as wildcard.

share|improve this answer

edited 7 hours ago

answered 7 hours ago

KulfyKulfy

7,5901010 gold badges3131 silver badges5858 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This answer will match the second occurrence of eni=10.*10**9 in a new line and will change it with eni=10.*10**8. Run it only once.
  
  – Raffa
  6 hours ago
  

  
  
  
  

add a comment | 

Using sed:

sed -i ': 1 ; N ; $!b1 ; s/eni=10.*10**9/eni=10.*10**8/2' filename

/ is one of the delimiters and is the escape character. is used so that bash won't interpret special characters as some command, like * as wildcard.

share|improve this answer

edited 7 hours ago

answered 7 hours ago

KulfyKulfy

7,5901010 gold badges3131 silver badges5858 bronze badges

sed -i ': 1 ; N ; $!b1 ; s/eni=10.*10**9/eni=10.*10**8/2' filename

share|improve this answer

edited 7 hours ago

answered 7 hours ago

KulfyKulfy

7,5901010 gold badges3131 silver badges5858 bronze badges

answered 7 hours ago

KulfyKulfy

7,5901010 gold badges3131 silver badges5858 bronze badges

answered 7 hours ago

KulfyKulfy

7,5901010 gold badges3131 silver badges5858 bronze badges

0

Since Ubuntu now ships with GNU Awk v4.0+ (which provides an inplace module) you could do something like

gawk -i inplace '/eni=/ if (++c == 2) sub(/10**9/,"10**8") 1' file

You can make the regular expressions /eni=/ and/or /10**9/ more or less specific as required.

share|improve this answer

answered 3 hours ago

steeldriversteeldriver

78.4k1212 gold badges129129 silver badges213213 bronze badges

add a comment | 

0

Since Ubuntu now ships with GNU Awk v4.0+ (which provides an inplace module) you could do something like

gawk -i inplace '/eni=/ if (++c == 2) sub(/10**9/,"10**8") 1' file

You can make the regular expressions /eni=/ and/or /10**9/ more or less specific as required.

share|improve this answer

answered 3 hours ago

steeldriversteeldriver

78.4k1212 gold badges129129 silver badges213213 bronze badges

add a comment | 

Since Ubuntu now ships with GNU Awk v4.0+ (which provides an inplace module) you could do something like

gawk -i inplace '/eni=/ if (++c == 2) sub(/10**9/,"10**8") 1' file

You can make the regular expressions /eni=/ and/or /10**9/ more or less specific as required.

share|improve this answer

answered 3 hours ago

steeldriversteeldriver

78.4k1212 gold badges129129 silver badges213213 bronze badges

gawk -i inplace '/eni=/ if (++c == 2) sub(/10**9/,"10**8") 1' file

share|improve this answer

answered 3 hours ago

steeldriversteeldriver

78.4k1212 gold badges129129 silver badges213213 bronze badges

answered 3 hours ago

steeldriversteeldriver

78.4k1212 gold badges129129 silver badges213213 bronze badges

answered 3 hours ago

steeldriversteeldriver

78.4k1212 gold badges129129 silver badges213213 bronze badges