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0

I am currently doing:

cat file1 file2 | sort -k1,1 > temp_file
command [options] -i temp_file > result_file

-i specifies the command input, in this case the file; I want a way to do this without explicitly specifying a temp_file.

cat file1 file2 | sort -k1,1 | command [options] -i > result_file fails, complaining there's no file after the -i.

I also tried xargs but that led to execution on every line of content instead of on the file.

bash shell-script

share|improve this question

edited 2 days ago

K7AAY

909928

asked 2 days ago

codeprimate123codeprimate123

31

New contributor

codeprimate123 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  How can i know if it does or not?
  
  – codeprimate123
  2 days ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Does your system provide either /dev/stdin or /proc/self/fd/0? If so you might be able to use them as the filename after the -i, i.e. sort -k1,1 file1 file2 | command [options] -i /dev/stdin (no cat needed). A big limitation of piped input is that the program can not use the lseek or seek calls on it so the program must be written to process the data sequentially or else provide its own buffering.
  
  – icarus
  2 days ago
  

  
  
  
  

add a comment | 

0

I am currently doing:

cat file1 file2 | sort -k1,1 > temp_file
command [options] -i temp_file > result_file

-i specifies the command input, in this case the file; I want a way to do this without explicitly specifying a temp_file.

cat file1 file2 | sort -k1,1 | command [options] -i > result_file fails, complaining there's no file after the -i.

I also tried xargs but that led to execution on every line of content instead of on the file.

bash shell-script

share|improve this question

edited 2 days ago

K7AAY

909928

asked 2 days ago

codeprimate123codeprimate123

31

New contributor

codeprimate123 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  How can i know if it does or not?
  
  – codeprimate123
  2 days ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Does your system provide either /dev/stdin or /proc/self/fd/0? If so you might be able to use them as the filename after the -i, i.e. sort -k1,1 file1 file2 | command [options] -i /dev/stdin (no cat needed). A big limitation of piped input is that the program can not use the lseek or seek calls on it so the program must be written to process the data sequentially or else provide its own buffering.
  
  – icarus
  2 days ago
  

  
  
  
  

add a comment | 

I am currently doing:

cat file1 file2 | sort -k1,1 > temp_file
command [options] -i temp_file > result_file

-i specifies the command input, in this case the file; I want a way to do this without explicitly specifying a temp_file.

cat file1 file2 | sort -k1,1 | command [options] -i > result_file fails, complaining there's no file after the -i.

I also tried xargs but that led to execution on every line of content instead of on the file.

bash shell-script

share|improve this question

edited 2 days ago

K7AAY

909928

asked 2 days ago

codeprimate123codeprimate123

31

New contributor

codeprimate123 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

cat file1 file2 | sort -k1,1 > temp_file
command [options] -i temp_file > result_file

share|improve this question

edited 2 days ago

K7AAY

909928

asked 2 days ago

codeprimate123codeprimate123

31

New contributor

codeprimate123 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 2 days ago

K7AAY

909928

asked 2 days ago

codeprimate123codeprimate123

31

New contributor

codeprimate123 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

edited 2 days ago

K7AAY

909928

edited 2 days ago

K7AAY

909928

asked 2 days ago

codeprimate123codeprimate123

31

New contributor

codeprimate123 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked 2 days ago

codeprimate123codeprimate123

31

1 Answer
1

active

oldest

votes

4

Some applications understand - there to mean stdin (check its man page), so

sort... | cmd -i - > result.txt

Most systems have a /dev/stdin special file (same as /dev/fd/0), which when open behaves like duplicating stdin, so:

sort... | cmd -i /dev/stdin > result.txt

With some shells (ksh, zsh, bash), you can also write it:

cmd -i <(sort...) > result.txt

While that would work, that file is a pipe so is not seekable. Some cmds may require a seekable file or a regular file and would fail if the file is a pipe. Then, you would have no other option than using a temporary file.

With zsh, you can use the =(...) form of process substitution:

cmd -i =(sort ...) > result.txt

for zsh to create and populate and cleanup the temporary file automatically.

Same with fish, using psub:

cmd -i (sort... | psub -f) > result.txt

With bash, still using a /dev/fd/x file but this time on a regular temporary file, deleted straight after it's opened for a more reliable clean-up:

tmp=$(mktemp) && 
 rm -f -- "$file" &&
 sort... >&3 3>&- 4<&- &&
 cmd -i /dev/fd/4 3>&-
 3> "$tmp" 4< "$tmp"

share|improve this answer

edited 2 days ago

answered 2 days ago

Stéphane ChazelasStéphane Chazelas

312k57592948

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  The first solution worked, using the - it processed the as it was a file. I will try and remember the others as well. Great answer, thank you!
  
  – codeprimate123
  2 days ago
  

  
  
  
  

add a comment | 

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4

Some applications understand - there to mean stdin (check its man page), so

sort... | cmd -i - > result.txt

Most systems have a /dev/stdin special file (same as /dev/fd/0), which when open behaves like duplicating stdin, so:

sort... | cmd -i /dev/stdin > result.txt

With some shells (ksh, zsh, bash), you can also write it:

cmd -i <(sort...) > result.txt

While that would work, that file is a pipe so is not seekable. Some cmds may require a seekable file or a regular file and would fail if the file is a pipe. Then, you would have no other option than using a temporary file.

With zsh, you can use the =(...) form of process substitution:

cmd -i =(sort ...) > result.txt

for zsh to create and populate and cleanup the temporary file automatically.

Same with fish, using psub:

cmd -i (sort... | psub -f) > result.txt

With bash, still using a /dev/fd/x file but this time on a regular temporary file, deleted straight after it's opened for a more reliable clean-up:

tmp=$(mktemp) && 
 rm -f -- "$file" &&
 sort... >&3 3>&- 4<&- &&
 cmd -i /dev/fd/4 3>&-
 3> "$tmp" 4< "$tmp"

share|improve this answer

edited 2 days ago

answered 2 days ago

Stéphane ChazelasStéphane Chazelas

312k57592948

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  The first solution worked, using the - it processed the as it was a file. I will try and remember the others as well. Great answer, thank you!
  
  – codeprimate123
  2 days ago
  

  
  
  
  

add a comment | 

4

Some applications understand - there to mean stdin (check its man page), so

sort... | cmd -i - > result.txt

Most systems have a /dev/stdin special file (same as /dev/fd/0), which when open behaves like duplicating stdin, so:

sort... | cmd -i /dev/stdin > result.txt

With some shells (ksh, zsh, bash), you can also write it:

cmd -i <(sort...) > result.txt

While that would work, that file is a pipe so is not seekable. Some cmds may require a seekable file or a regular file and would fail if the file is a pipe. Then, you would have no other option than using a temporary file.

With zsh, you can use the =(...) form of process substitution:

cmd -i =(sort ...) > result.txt

for zsh to create and populate and cleanup the temporary file automatically.

Same with fish, using psub:

cmd -i (sort... | psub -f) > result.txt

With bash, still using a /dev/fd/x file but this time on a regular temporary file, deleted straight after it's opened for a more reliable clean-up:

tmp=$(mktemp) && 
 rm -f -- "$file" &&
 sort... >&3 3>&- 4<&- &&
 cmd -i /dev/fd/4 3>&-
 3> "$tmp" 4< "$tmp"

share|improve this answer

edited 2 days ago

answered 2 days ago

Stéphane ChazelasStéphane Chazelas

312k57592948

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  The first solution worked, using the - it processed the as it was a file. I will try and remember the others as well. Great answer, thank you!
  
  – codeprimate123
  2 days ago
  

  
  
  
  

add a comment | 

Some applications understand - there to mean stdin (check its man page), so

sort... | cmd -i - > result.txt

Most systems have a /dev/stdin special file (same as /dev/fd/0), which when open behaves like duplicating stdin, so:

sort... | cmd -i /dev/stdin > result.txt

With some shells (ksh, zsh, bash), you can also write it:

cmd -i <(sort...) > result.txt

While that would work, that file is a pipe so is not seekable. Some cmds may require a seekable file or a regular file and would fail if the file is a pipe. Then, you would have no other option than using a temporary file.

With zsh, you can use the =(...) form of process substitution:

cmd -i =(sort ...) > result.txt

for zsh to create and populate and cleanup the temporary file automatically.

Same with fish, using psub:

cmd -i (sort... | psub -f) > result.txt

With bash, still using a /dev/fd/x file but this time on a regular temporary file, deleted straight after it's opened for a more reliable clean-up:

tmp=$(mktemp) && 
 rm -f -- "$file" &&
 sort... >&3 3>&- 4<&- &&
 cmd -i /dev/fd/4 3>&-
 3> "$tmp" 4< "$tmp"

share|improve this answer

edited 2 days ago

answered 2 days ago

Stéphane ChazelasStéphane Chazelas

312k57592948

sort... | cmd -i - > result.txt

sort... | cmd -i /dev/stdin > result.txt

cmd -i <(sort...) > result.txt

cmd -i =(sort ...) > result.txt

cmd -i (sort... | psub -f) > result.txt

tmp=$(mktemp) && 
 rm -f -- "$file" &&
 sort... >&3 3>&- 4<&- &&
 cmd -i /dev/fd/4 3>&-
 3> "$tmp" 4< "$tmp"

share|improve this answer

edited 2 days ago

answered 2 days ago

Stéphane ChazelasStéphane Chazelas

312k57592948

answered 2 days ago

Stéphane ChazelasStéphane Chazelas

312k57592948

answered 2 days ago

Stéphane ChazelasStéphane Chazelas

312k57592948