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3

1

I have a file called requirements.txt, each line has a package :

package1
package2
package3

I'm looking for a command that will take each line of requirements.txt and join them in one line, space separated.

So basically, I'm looking to generate the following command:

command package1 package2 package3

I tried using a for and applying command for each line of requirements.txt but it was much slower

command-line bash

share|improve this question

edited 8 hours ago

Mojimi

asked 9 hours ago

MojimiMojimi

13377 bronze badges

add a comment | 

3

1

I have a file called requirements.txt, each line has a package :

package1
package2
package3

I'm looking for a command that will take each line of requirements.txt and join them in one line, space separated.

So basically, I'm looking to generate the following command:

command package1 package2 package3

I tried using a for and applying command for each line of requirements.txt but it was much slower

command-line bash

share|improve this question

edited 8 hours ago

Mojimi

asked 9 hours ago

MojimiMojimi

13377 bronze badges

add a comment | 

I have a file called requirements.txt, each line has a package :

package1
package2
package3

I'm looking for a command that will take each line of requirements.txt and join them in one line, space separated.

So basically, I'm looking to generate the following command:

command package1 package2 package3

I tried using a for and applying command for each line of requirements.txt but it was much slower

command-line bash

share|improve this question

edited 8 hours ago

Mojimi

asked 9 hours ago

MojimiMojimi

13377 bronze badges

package1
package2
package3

command package1 package2 package3

share|improve this question

edited 8 hours ago

Mojimi

asked 9 hours ago

MojimiMojimi

13377 bronze badges

share|improve this question

edited 8 hours ago

Mojimi

asked 9 hours ago

MojimiMojimi

13377 bronze badges

asked 9 hours ago

MojimiMojimi

13377 bronze badges

asked 9 hours ago

MojimiMojimi

13377 bronze badges

3 Answers
3

active

oldest

votes

3

You can simply use bash redirection and command substitution to get the file contents as arguments to your command:

command $(<file)

This works because not only space is a valid word splitting character, but newline as well – you don’t need to substitute anything. However, in the case of many lines you will get an error referring to the shell’s ARG_MAX limit (as you will with substitution solutions). Use printf to built a list of arguments and xargs to built command lines from it to work around that:

printf "%s" $(<file) | xargs -0 command

Note that neither of these approaches work for lines containing whitespace characters (besides the newline of course) – fortunately package names don’t.

share|improve this answer

edited 8 hours ago

answered 8 hours ago

dessertdessert

28.7k66 gold badges8686 silver badges119119 bronze badges

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  Didn't know about it... really nice ;)
  
  – Ravexina
  8 hours ago
  

  
  
  
  

add a comment | 

2

Use tr and bash substitution:

command $(tr 'n' ' ' < requirements.txt)

for example:

echo $(tr 'n' ' ' < requirements.txt)

output would be:

package1 package2 package3

or:

sudo apt install -y $(tr 'n' ' ' < requirements.txt)

would install all packages.

share|improve this answer

answered 8 hours ago

RavexinaRavexina

35.9k1515 gold badges9797 silver badges126126 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  That is outputting "package3xe" to me
  
  – Mojimi
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  What is the output of file requirements.txt?
  
  – Ravexina
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  ASCII text, with CRLF line terminators (This file was created in windows and sent to docker)
  
  – Mojimi
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Run sudo apt install dos2unix then dos2unix requirements.txt to remove r (carriage returns) from your file it has been created on a windows machine I guess. or try $(tr 'rn' ' ') instead.
  
  – Ravexina
  8 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Figured it out, it worked with 'nr' , thanks for the hint
  
  – Mojimi
  8 hours ago
  

  
  
  
  

add a comment | 

2

You can use xargs, with the delimiter set to newline (n): this will ensure the arguments get passed correctly even if they contain whitespace:

xargs -rd'n' command < requirements.txt

share|improve this answer

answered 7 hours ago

steeldriversteeldriver

78k1212 gold badges129129 silver badges209209 bronze badges

add a comment | 

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3

You can simply use bash redirection and command substitution to get the file contents as arguments to your command:

command $(<file)

This works because not only space is a valid word splitting character, but newline as well – you don’t need to substitute anything. However, in the case of many lines you will get an error referring to the shell’s ARG_MAX limit (as you will with substitution solutions). Use printf to built a list of arguments and xargs to built command lines from it to work around that:

printf "%s" $(<file) | xargs -0 command

Note that neither of these approaches work for lines containing whitespace characters (besides the newline of course) – fortunately package names don’t.

share|improve this answer

edited 8 hours ago

answered 8 hours ago

dessertdessert

28.7k66 gold badges8686 silver badges119119 bronze badges

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  Didn't know about it... really nice ;)
  
  – Ravexina
  8 hours ago
  

  
  
  
  

add a comment | 

3

You can simply use bash redirection and command substitution to get the file contents as arguments to your command:

command $(<file)

This works because not only space is a valid word splitting character, but newline as well – you don’t need to substitute anything. However, in the case of many lines you will get an error referring to the shell’s ARG_MAX limit (as you will with substitution solutions). Use printf to built a list of arguments and xargs to built command lines from it to work around that:

printf "%s" $(<file) | xargs -0 command

Note that neither of these approaches work for lines containing whitespace characters (besides the newline of course) – fortunately package names don’t.

share|improve this answer

edited 8 hours ago

answered 8 hours ago

dessertdessert

28.7k66 gold badges8686 silver badges119119 bronze badges

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  Didn't know about it... really nice ;)
  
  – Ravexina
  8 hours ago
  

  
  
  
  

add a comment | 

You can simply use bash redirection and command substitution to get the file contents as arguments to your command:

command $(<file)

This works because not only space is a valid word splitting character, but newline as well – you don’t need to substitute anything. However, in the case of many lines you will get an error referring to the shell’s ARG_MAX limit (as you will with substitution solutions). Use printf to built a list of arguments and xargs to built command lines from it to work around that:

printf "%s" $(<file) | xargs -0 command

Note that neither of these approaches work for lines containing whitespace characters (besides the newline of course) – fortunately package names don’t.

share|improve this answer

edited 8 hours ago

answered 8 hours ago

dessertdessert

28.7k66 gold badges8686 silver badges119119 bronze badges

command $(<file)

printf "%s" $(<file) | xargs -0 command

share|improve this answer

edited 8 hours ago

answered 8 hours ago

dessertdessert

28.7k66 gold badges8686 silver badges119119 bronze badges

answered 8 hours ago

dessertdessert

28.7k66 gold badges8686 silver badges119119 bronze badges

answered 8 hours ago

dessertdessert

28.7k66 gold badges8686 silver badges119119 bronze badges

2

Use tr and bash substitution:

command $(tr 'n' ' ' < requirements.txt)

for example:

echo $(tr 'n' ' ' < requirements.txt)

output would be:

package1 package2 package3

or:

sudo apt install -y $(tr 'n' ' ' < requirements.txt)

would install all packages.

share|improve this answer

answered 8 hours ago

RavexinaRavexina

35.9k1515 gold badges9797 silver badges126126 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  That is outputting "package3xe" to me
  
  – Mojimi
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  What is the output of file requirements.txt?
  
  – Ravexina
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  ASCII text, with CRLF line terminators (This file was created in windows and sent to docker)
  
  – Mojimi
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Run sudo apt install dos2unix then dos2unix requirements.txt to remove r (carriage returns) from your file it has been created on a windows machine I guess. or try $(tr 'rn' ' ') instead.
  
  – Ravexina
  8 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Figured it out, it worked with 'nr' , thanks for the hint
  
  – Mojimi
  8 hours ago
  

  
  
  
  

add a comment | 

2

Use tr and bash substitution:

command $(tr 'n' ' ' < requirements.txt)

for example:

echo $(tr 'n' ' ' < requirements.txt)

output would be:

package1 package2 package3

or:

sudo apt install -y $(tr 'n' ' ' < requirements.txt)

would install all packages.

share|improve this answer

answered 8 hours ago

RavexinaRavexina

35.9k1515 gold badges9797 silver badges126126 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  That is outputting "package3xe" to me
  
  – Mojimi
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  What is the output of file requirements.txt?
  
  – Ravexina
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  ASCII text, with CRLF line terminators (This file was created in windows and sent to docker)
  
  – Mojimi
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Run sudo apt install dos2unix then dos2unix requirements.txt to remove r (carriage returns) from your file it has been created on a windows machine I guess. or try $(tr 'rn' ' ') instead.
  
  – Ravexina
  8 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Figured it out, it worked with 'nr' , thanks for the hint
  
  – Mojimi
  8 hours ago
  

  
  
  
  

add a comment | 

Use tr and bash substitution:

command $(tr 'n' ' ' < requirements.txt)

for example:

echo $(tr 'n' ' ' < requirements.txt)

output would be:

package1 package2 package3

or:

sudo apt install -y $(tr 'n' ' ' < requirements.txt)

would install all packages.

share|improve this answer

answered 8 hours ago

RavexinaRavexina

35.9k1515 gold badges9797 silver badges126126 bronze badges

command $(tr 'n' ' ' < requirements.txt)

echo $(tr 'n' ' ' < requirements.txt)

package1 package2 package3

sudo apt install -y $(tr 'n' ' ' < requirements.txt)

share|improve this answer

answered 8 hours ago

RavexinaRavexina

35.9k1515 gold badges9797 silver badges126126 bronze badges

answered 8 hours ago

RavexinaRavexina

35.9k1515 gold badges9797 silver badges126126 bronze badges

answered 8 hours ago

RavexinaRavexina

35.9k1515 gold badges9797 silver badges126126 bronze badges

2

You can use xargs, with the delimiter set to newline (n): this will ensure the arguments get passed correctly even if they contain whitespace:

xargs -rd'n' command < requirements.txt

share|improve this answer

answered 7 hours ago

steeldriversteeldriver

78k1212 gold badges129129 silver badges209209 bronze badges

add a comment | 

2

You can use xargs, with the delimiter set to newline (n): this will ensure the arguments get passed correctly even if they contain whitespace:

xargs -rd'n' command < requirements.txt

share|improve this answer

answered 7 hours ago

steeldriversteeldriver

78k1212 gold badges129129 silver badges209209 bronze badges

add a comment | 

You can use xargs, with the delimiter set to newline (n): this will ensure the arguments get passed correctly even if they contain whitespace:

xargs -rd'n' command < requirements.txt

share|improve this answer

answered 7 hours ago

steeldriversteeldriver

78k1212 gold badges129129 silver badges209209 bronze badges

xargs -rd'n' command < requirements.txt

share|improve this answer

answered 7 hours ago

steeldriversteeldriver

78k1212 gold badges129129 silver badges209209 bronze badges

answered 7 hours ago

steeldriversteeldriver

78k1212 gold badges129129 silver badges209209 bronze badges

answered 7 hours ago

steeldriversteeldriver

78k1212 gold badges129129 silver badges209209 bronze badges