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12

I would like to split a string into two halves and print them sequentially. For example:

abcdef

into

abc
def

Is there a simple way to do it, or it needs some string processing?

bash string

share|improve this question

edited May 30 at 21:23

Jeff Schaller♦

46.8k1167152

asked May 30 at 21:11

Gabriel DiegoGabriel Diego

1665

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  How do you have the incoming string? Variable? Stdin? Other?
  
  – Jeff Schaller♦
  May 30 at 21:24
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  In a variable. It doesn't really matter, as anything can be worked out (stdin input can be put in a variable).
  
  – Gabriel Diego
  May 30 at 21:27
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  It matters for efficiency, especially if it can be possibly-gigantic. And also for convenience.
  
  – Peter Cordes
  May 31 at 10:36
  
  

  
  
  
  

add a comment | 

12

I would like to split a string into two halves and print them sequentially. For example:

abcdef

into

abc
def

Is there a simple way to do it, or it needs some string processing?

bash string

share|improve this question

edited May 30 at 21:23

Jeff Schaller♦

46.8k1167152

asked May 30 at 21:11

Gabriel DiegoGabriel Diego

1665

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  How do you have the incoming string? Variable? Stdin? Other?
  
  – Jeff Schaller♦
  May 30 at 21:24
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  In a variable. It doesn't really matter, as anything can be worked out (stdin input can be put in a variable).
  
  – Gabriel Diego
  May 30 at 21:27
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  It matters for efficiency, especially if it can be possibly-gigantic. And also for convenience.
  
  – Peter Cordes
  May 31 at 10:36
  
  

  
  
  
  

add a comment | 

I would like to split a string into two halves and print them sequentially. For example:

abcdef

into

abc
def

Is there a simple way to do it, or it needs some string processing?

bash string

share|improve this question

edited May 30 at 21:23

Jeff Schaller♦

46.8k1167152

asked May 30 at 21:11

Gabriel DiegoGabriel Diego

1665

abcdef

abc
def

share|improve this question

edited May 30 at 21:23

Jeff Schaller♦

46.8k1167152

asked May 30 at 21:11

Gabriel DiegoGabriel Diego

1665

share|improve this question

edited May 30 at 21:23

Jeff Schaller♦

46.8k1167152

asked May 30 at 21:11

Gabriel DiegoGabriel Diego

1665

edited May 30 at 21:23

Jeff Schaller♦

46.8k1167152

edited May 30 at 21:23

Jeff Schaller♦

46.8k1167152

asked May 30 at 21:11

Gabriel DiegoGabriel Diego

1665

asked May 30 at 21:11

Gabriel DiegoGabriel Diego

1665

4 Answers
4

active

oldest

votes

16

Using parameter expansion and shell arithmetic:

The first half of the variable will be:

$var:0:$#var/2

The second half of the variable will be:

$var:$#var/2

---

so you could use:

printf '%sn' "$var:0:$#var/2" "$var:$#var/2"

---

You could also use the following awk command:

awk 'BEGINFS=""for(i=1;i<=NF/2;i++)printf $iprintf "n"for(i=NF/2+1;i<=NF;i++)printf $iprintf "n"'

---

$ echo abcdef | awk 'BEGINFS=""for(i=1;i<=NF/2;i++)printf $iprintf "n"for(i=NF/2+1;i<=NF;i++)printf $iprintf "n"'
abc
def

share|improve this answer

edited May 30 at 22:07

answered May 30 at 21:18

Jesse_bJesse_b

16.7k34183

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks for the response!
  
  – Gabriel Diego
  May 30 at 21:19
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  concise and elegant solution.
  
  – Dudi Boy
  May 30 at 21:32
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  You can get rid of the $((...)); the off and len part of the $var:off:len substitution are already evaluated as arithmetic expressions. Example: foo=01234567; echo "$foo:0:$#foo/2 $foo:$#foo/2". That's documented, and it's the same in zsh and ksh93 as in bash.
  
  – mosvy
  May 30 at 21:47
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  Note: If the length of the string is odd, this will still split it into two parts, but the second will be a character longer.
  
  – peterh
  May 31 at 7:39
  

  
  
  
  

add a comment | 

8

Using split, here strings and command substitution:

var=abcdef
printf '%sn' "$(split -n1/2 <<<$var)" "$(split -n2/2 <<<$var)"

share|improve this answer

answered May 30 at 21:42

FreddyFreddy

4,8331521

add a comment | 

7

Another awk script can be:

echo abcdef | awk 'print substr($0,1,length/2); print substr($0,length/2+1)'

share|improve this answer

answered May 30 at 21:37

Dudi BoyDudi Boy

40627

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Note that it doesn't work with mawk or busybox awk because of the syntax ambiguity of division / and the /ERE/ operator, and the special case of () being optional for length (still those implementations are not POSIX compliant in that case). Using length() or length($0) here instead of length would help for those. You could also do awk 'BEGINhalf = int(length(ARGV[1]) / 2); print substr(ARGV[1], 1, half) ORS substr(ARGV[1], half+1)' abcdef which would save the pipe and extra process and make it work even if the string contains newline characters.
  
  – Stéphane Chazelas
  May 31 at 10:55
  
  

  
  
  
  

add a comment | 

1

Python 3

s = input() # Take one line of input from stdin.
x = len(s) // 2 # Get middle of string. "//" is floor division
print(s[:x], s[x:], sep="n") # Print "s" up to "x", then "s" past "x", joined on newlines.

For example,

$ echo abcdef | python3 -c 's = input(); x = len(s) // 2; print(s[:x], s[x:], sep="n")'
abc
def

If the string length is not an even number, the second line will be longer. E.g.

$ echo abcdefg | python3 -c 's = input(); x= len(s) // 2; print(s[:x], s[x:], sep="n")'
abc
defg

share|improve this answer

edited May 31 at 14:07

answered May 31 at 14:02

wjandreawjandrea

590414

add a comment | 

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16

Using parameter expansion and shell arithmetic:

The first half of the variable will be:

$var:0:$#var/2

The second half of the variable will be:

$var:$#var/2

---

so you could use:

printf '%sn' "$var:0:$#var/2" "$var:$#var/2"

---

You could also use the following awk command:

awk 'BEGINFS=""for(i=1;i<=NF/2;i++)printf $iprintf "n"for(i=NF/2+1;i<=NF;i++)printf $iprintf "n"'

---

$ echo abcdef | awk 'BEGINFS=""for(i=1;i<=NF/2;i++)printf $iprintf "n"for(i=NF/2+1;i<=NF;i++)printf $iprintf "n"'
abc
def

share|improve this answer

edited May 30 at 22:07

answered May 30 at 21:18

Jesse_bJesse_b

16.7k34183

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks for the response!
  
  – Gabriel Diego
  May 30 at 21:19
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  concise and elegant solution.
  
  – Dudi Boy
  May 30 at 21:32
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  You can get rid of the $((...)); the off and len part of the $var:off:len substitution are already evaluated as arithmetic expressions. Example: foo=01234567; echo "$foo:0:$#foo/2 $foo:$#foo/2". That's documented, and it's the same in zsh and ksh93 as in bash.
  
  – mosvy
  May 30 at 21:47
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  Note: If the length of the string is odd, this will still split it into two parts, but the second will be a character longer.
  
  – peterh
  May 31 at 7:39
  

  
  
  
  

add a comment | 

16

Using parameter expansion and shell arithmetic:

The first half of the variable will be:

$var:0:$#var/2

The second half of the variable will be:

$var:$#var/2

---

so you could use:

printf '%sn' "$var:0:$#var/2" "$var:$#var/2"

---

You could also use the following awk command:

awk 'BEGINFS=""for(i=1;i<=NF/2;i++)printf $iprintf "n"for(i=NF/2+1;i<=NF;i++)printf $iprintf "n"'

---

$ echo abcdef | awk 'BEGINFS=""for(i=1;i<=NF/2;i++)printf $iprintf "n"for(i=NF/2+1;i<=NF;i++)printf $iprintf "n"'
abc
def

share|improve this answer

edited May 30 at 22:07

answered May 30 at 21:18

Jesse_bJesse_b

16.7k34183

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks for the response!
  
  – Gabriel Diego
  May 30 at 21:19
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  concise and elegant solution.
  
  – Dudi Boy
  May 30 at 21:32
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  You can get rid of the $((...)); the off and len part of the $var:off:len substitution are already evaluated as arithmetic expressions. Example: foo=01234567; echo "$foo:0:$#foo/2 $foo:$#foo/2". That's documented, and it's the same in zsh and ksh93 as in bash.
  
  – mosvy
  May 30 at 21:47
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  Note: If the length of the string is odd, this will still split it into two parts, but the second will be a character longer.
  
  – peterh
  May 31 at 7:39
  

  
  
  
  

add a comment | 

Using parameter expansion and shell arithmetic:

The first half of the variable will be:

$var:0:$#var/2

The second half of the variable will be:

$var:$#var/2

---

so you could use:

printf '%sn' "$var:0:$#var/2" "$var:$#var/2"

---

You could also use the following awk command:

awk 'BEGINFS=""for(i=1;i<=NF/2;i++)printf $iprintf "n"for(i=NF/2+1;i<=NF;i++)printf $iprintf "n"'

---

$ echo abcdef | awk 'BEGINFS=""for(i=1;i<=NF/2;i++)printf $iprintf "n"for(i=NF/2+1;i<=NF;i++)printf $iprintf "n"'
abc
def

share|improve this answer

edited May 30 at 22:07

answered May 30 at 21:18

Jesse_bJesse_b

16.7k34183

$var:0:$#var/2

$var:$#var/2

printf '%sn' "$var:0:$#var/2" "$var:$#var/2"

awk 'BEGINFS=""for(i=1;i<=NF/2;i++)printf $iprintf "n"for(i=NF/2+1;i<=NF;i++)printf $iprintf "n"'

$ echo abcdef | awk 'BEGINFS=""for(i=1;i<=NF/2;i++)printf $iprintf "n"for(i=NF/2+1;i<=NF;i++)printf $iprintf "n"'
abc
def

share|improve this answer

edited May 30 at 22:07

answered May 30 at 21:18

Jesse_bJesse_b

16.7k34183

answered May 30 at 21:18

Jesse_bJesse_b

16.7k34183

answered May 30 at 21:18

Jesse_bJesse_b

16.7k34183

8

Using split, here strings and command substitution:

var=abcdef
printf '%sn' "$(split -n1/2 <<<$var)" "$(split -n2/2 <<<$var)"

share|improve this answer

answered May 30 at 21:42

FreddyFreddy

4,8331521

add a comment | 

8

Using split, here strings and command substitution:

var=abcdef
printf '%sn' "$(split -n1/2 <<<$var)" "$(split -n2/2 <<<$var)"

share|improve this answer

answered May 30 at 21:42

FreddyFreddy

4,8331521

add a comment | 

Using split, here strings and command substitution:

var=abcdef
printf '%sn' "$(split -n1/2 <<<$var)" "$(split -n2/2 <<<$var)"

share|improve this answer

answered May 30 at 21:42

FreddyFreddy

4,8331521

var=abcdef
printf '%sn' "$(split -n1/2 <<<$var)" "$(split -n2/2 <<<$var)"

share|improve this answer

answered May 30 at 21:42

FreddyFreddy

4,8331521

answered May 30 at 21:42

FreddyFreddy

4,8331521

answered May 30 at 21:42

FreddyFreddy

4,8331521

7

Another awk script can be:

echo abcdef | awk 'print substr($0,1,length/2); print substr($0,length/2+1)'

share|improve this answer

answered May 30 at 21:37

Dudi BoyDudi Boy

40627

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Note that it doesn't work with mawk or busybox awk because of the syntax ambiguity of division / and the /ERE/ operator, and the special case of () being optional for length (still those implementations are not POSIX compliant in that case). Using length() or length($0) here instead of length would help for those. You could also do awk 'BEGINhalf = int(length(ARGV[1]) / 2); print substr(ARGV[1], 1, half) ORS substr(ARGV[1], half+1)' abcdef which would save the pipe and extra process and make it work even if the string contains newline characters.
  
  – Stéphane Chazelas
  May 31 at 10:55
  
  

  
  
  
  

add a comment | 

7

Another awk script can be:

echo abcdef | awk 'print substr($0,1,length/2); print substr($0,length/2+1)'

share|improve this answer

answered May 30 at 21:37

Dudi BoyDudi Boy

40627

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Note that it doesn't work with mawk or busybox awk because of the syntax ambiguity of division / and the /ERE/ operator, and the special case of () being optional for length (still those implementations are not POSIX compliant in that case). Using length() or length($0) here instead of length would help for those. You could also do awk 'BEGINhalf = int(length(ARGV[1]) / 2); print substr(ARGV[1], 1, half) ORS substr(ARGV[1], half+1)' abcdef which would save the pipe and extra process and make it work even if the string contains newline characters.
  
  – Stéphane Chazelas
  May 31 at 10:55
  
  

  
  
  
  

add a comment | 

Another awk script can be:

echo abcdef | awk 'print substr($0,1,length/2); print substr($0,length/2+1)'

share|improve this answer

answered May 30 at 21:37

Dudi BoyDudi Boy

40627

echo abcdef | awk 'print substr($0,1,length/2); print substr($0,length/2+1)'

share|improve this answer

answered May 30 at 21:37

Dudi BoyDudi Boy

40627

answered May 30 at 21:37

Dudi BoyDudi Boy

40627

answered May 30 at 21:37

Dudi BoyDudi Boy

40627

1

Python 3

s = input() # Take one line of input from stdin.
x = len(s) // 2 # Get middle of string. "//" is floor division
print(s[:x], s[x:], sep="n") # Print "s" up to "x", then "s" past "x", joined on newlines.

For example,

$ echo abcdef | python3 -c 's = input(); x = len(s) // 2; print(s[:x], s[x:], sep="n")'
abc
def

If the string length is not an even number, the second line will be longer. E.g.

$ echo abcdefg | python3 -c 's = input(); x= len(s) // 2; print(s[:x], s[x:], sep="n")'
abc
defg

share|improve this answer

edited May 31 at 14:07

answered May 31 at 14:02

wjandreawjandrea

590414

add a comment | 

1

Python 3

s = input() # Take one line of input from stdin.
x = len(s) // 2 # Get middle of string. "//" is floor division
print(s[:x], s[x:], sep="n") # Print "s" up to "x", then "s" past "x", joined on newlines.

For example,

$ echo abcdef | python3 -c 's = input(); x = len(s) // 2; print(s[:x], s[x:], sep="n")'
abc
def

If the string length is not an even number, the second line will be longer. E.g.

$ echo abcdefg | python3 -c 's = input(); x= len(s) // 2; print(s[:x], s[x:], sep="n")'
abc
defg

share|improve this answer

edited May 31 at 14:07

answered May 31 at 14:02

wjandreawjandrea

590414

add a comment | 

Python 3

s = input() # Take one line of input from stdin.
x = len(s) // 2 # Get middle of string. "//" is floor division
print(s[:x], s[x:], sep="n") # Print "s" up to "x", then "s" past "x", joined on newlines.

For example,

$ echo abcdef | python3 -c 's = input(); x = len(s) // 2; print(s[:x], s[x:], sep="n")'
abc
def

If the string length is not an even number, the second line will be longer. E.g.

$ echo abcdefg | python3 -c 's = input(); x= len(s) // 2; print(s[:x], s[x:], sep="n")'
abc
defg

share|improve this answer

edited May 31 at 14:07

answered May 31 at 14:02

wjandreawjandrea

590414

s = input() # Take one line of input from stdin.
x = len(s) // 2 # Get middle of string. "//" is floor division
print(s[:x], s[x:], sep="n") # Print "s" up to "x", then "s" past "x", joined on newlines.

$ echo abcdef | python3 -c 's = input(); x = len(s) // 2; print(s[:x], s[x:], sep="n")'
abc
def

$ echo abcdefg | python3 -c 's = input(); x= len(s) // 2; print(s[:x], s[x:], sep="n")'
abc
defg

share|improve this answer

edited May 31 at 14:07

answered May 31 at 14:02

wjandreawjandrea

590414

answered May 31 at 14:02

wjandreawjandrea

590414

answered May 31 at 14:02

wjandreawjandrea

590414