In bash, how do I pass the entire contents of a file to a program as a single string?
I want to run a C program with the contents of a file as input (including newline characters), but the program only accepts a single string as input.
How do I pipe/redirect/pass the file contents into the program as a single string?
cat "$filename" > ./program_name doesn't preserve the content as a single string, and most other solutions seem to pass the command as the literal text of the command.
string bash input pipe io-redirection
asked Nov 14 '18 at 4:48
DanielDaniel
927
add a comment |
I want to run a C program with the contents of a file as input (including newline characters), but the program only accepts a single string as input.
How do I pipe/redirect/pass the file contents into the program as a single string?
cat "$filename" > ./program_name doesn't preserve the content as a single string, and most other solutions seem to pass the command as the literal text of the command.
string bash input pipe io-redirection
asked Nov 14 '18 at 4:48
DanielDaniel
927
1
While not solving your immediate issue, is there any reason you are using command line arguments instead of reading standard input?
– Mad Physicist
Nov 14 '18 at 5:09
1
Why don't you read file in program rather than passing it as an argument. Let's say your file location is dynamic you could pass it then. Think about that if file is very big then it may cause slowness to your program.
– RavinderSingh13
Nov 14 '18 at 5:10
Those are both great suggestions, and I'll probably implement those changes soon. I only posted this question to share the fix I found in case anyone else was in a situation where they couldn't modify the program in question. I'd definitely advocate posting those as answers too!
– Daniel
Nov 14 '18 at 5:26
add a comment |
I want to run a C program with the contents of a file as input (including newline characters), but the program only accepts a single string as input.
How do I pipe/redirect/pass the file contents into the program as a single string?
cat "$filename" > ./program_name doesn't preserve the content as a single string, and most other solutions seem to pass the command as the literal text of the command.
string bash input pipe io-redirection
asked Nov 14 '18 at 4:48
DanielDaniel
927
I want to run a C program with the contents of a file as input (including newline characters), but the program only accepts a single string as input.
How do I pipe/redirect/pass the file contents into the program as a single string?
cat "$filename" > ./program_name doesn't preserve the content as a single string, and most other solutions seem to pass the command as the literal text of the command.
string bash input pipe io-redirection
string bash input pipe io-redirection
asked Nov 14 '18 at 4:48
DanielDaniel
927
asked Nov 14 '18 at 4:48
DanielDaniel
927
asked Nov 14 '18 at 4:48
DanielDaniel
927
asked Nov 14 '18 at 4:48
DanielDaniel
927
asked Nov 14 '18 at 4:48
DanielDaniel
927
927
1
While not solving your immediate issue, is there any reason you are using command line arguments instead of reading standard input?
– Mad Physicist
Nov 14 '18 at 5:09
1
Why don't you read file in program rather than passing it as an argument. Let's say your file location is dynamic you could pass it then. Think about that if file is very big then it may cause slowness to your program.
– RavinderSingh13
Nov 14 '18 at 5:10
Those are both great suggestions, and I'll probably implement those changes soon. I only posted this question to share the fix I found in case anyone else was in a situation where they couldn't modify the program in question. I'd definitely advocate posting those as answers too!
– Daniel
Nov 14 '18 at 5:26
add a comment |
1
While not solving your immediate issue, is there any reason you are using command line arguments instead of reading standard input?
– Mad Physicist
Nov 14 '18 at 5:09
1
Why don't you read file in program rather than passing it as an argument. Let's say your file location is dynamic you could pass it then. Think about that if file is very big then it may cause slowness to your program.
– RavinderSingh13
Nov 14 '18 at 5:10
Those are both great suggestions, and I'll probably implement those changes soon. I only posted this question to share the fix I found in case anyone else was in a situation where they couldn't modify the program in question. I'd definitely advocate posting those as answers too!
– Daniel
Nov 14 '18 at 5:26
1
1
While not solving your immediate issue, is there any reason you are using command line arguments instead of reading standard input?
– Mad Physicist
Nov 14 '18 at 5:09
While not solving your immediate issue, is there any reason you are using command line arguments instead of reading standard input?
– Mad Physicist
Nov 14 '18 at 5:09
1
1
Why don't you read file in program rather than passing it as an argument. Let's say your file location is dynamic you could pass it then. Think about that if file is very big then it may cause slowness to your program.
– RavinderSingh13
Nov 14 '18 at 5:10
Why don't you read file in program rather than passing it as an argument. Let's say your file location is dynamic you could pass it then. Think about that if file is very big then it may cause slowness to your program.
– RavinderSingh13
Nov 14 '18 at 5:10
Those are both great suggestions, and I'll probably implement those changes soon. I only posted this question to share the fix I found in case anyone else was in a situation where they couldn't modify the program in question. I'd definitely advocate posting those as answers too!
– Daniel
Nov 14 '18 at 5:26
Those are both great suggestions, and I'll probably implement those changes soon. I only posted this question to share the fix I found in case anyone else was in a situation where they couldn't modify the program in question. I'd definitely advocate posting those as answers too!
– Daniel
Nov 14 '18 at 5:26
add a comment |
1 Answer
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./program_name "$(< "$filename")" should do the trick.
$(), similar to `` runs its contents as a sub-process and returns the result, so $(< "$filename") will redirect the contents of the file as the output of the sub-process.
"$(<"$filename")" does the same thing, except since it's wrapped in quotes, bash will not perform word splitting
answered Nov 14 '18 at 4:48
DanielDaniel
927
1
Bash allows you to use$(< "$filename"), which is a little bit faster than usingcat. Also, the key mechanic that quotes suppress in this case is "word splitting".
– Benjamin W.
Nov 14 '18 at 5:52
add a comment |
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./program_name "$(< "$filename")" should do the trick.
$(), similar to `` runs its contents as a sub-process and returns the result, so $(< "$filename") will redirect the contents of the file as the output of the sub-process.
"$(<"$filename")" does the same thing, except since it's wrapped in quotes, bash will not perform word splitting
answered Nov 14 '18 at 4:48
DanielDaniel
927
1
Bash allows you to use$(< "$filename"), which is a little bit faster than usingcat. Also, the key mechanic that quotes suppress in this case is "word splitting".
– Benjamin W.
Nov 14 '18 at 5:52
add a comment |
./program_name "$(< "$filename")" should do the trick.
$(), similar to `` runs its contents as a sub-process and returns the result, so $(< "$filename") will redirect the contents of the file as the output of the sub-process.
"$(<"$filename")" does the same thing, except since it's wrapped in quotes, bash will not perform word splitting
answered Nov 14 '18 at 4:48
DanielDaniel
927
1
Bash allows you to use$(< "$filename"), which is a little bit faster than usingcat. Also, the key mechanic that quotes suppress in this case is "word splitting".
– Benjamin W.
Nov 14 '18 at 5:52
add a comment |
./program_name "$(< "$filename")" should do the trick.
$(), similar to `` runs its contents as a sub-process and returns the result, so $(< "$filename") will redirect the contents of the file as the output of the sub-process.
"$(<"$filename")" does the same thing, except since it's wrapped in quotes, bash will not perform word splitting
answered Nov 14 '18 at 4:48
DanielDaniel
927
./program_name "$(< "$filename")" should do the trick.
$(), similar to `` runs its contents as a sub-process and returns the result, so $(< "$filename") will redirect the contents of the file as the output of the sub-process.
"$(<"$filename")" does the same thing, except since it's wrapped in quotes, bash will not perform word splitting
answered Nov 14 '18 at 4:48
DanielDaniel
927
edited Nov 14 '18 at 7:07
answered Nov 14 '18 at 4:48
DanielDaniel
927
answered Nov 14 '18 at 4:48
DanielDaniel
927
answered Nov 14 '18 at 4:48
DanielDaniel
927
927
1
Bash allows you to use$(< "$filename"), which is a little bit faster than usingcat. Also, the key mechanic that quotes suppress in this case is "word splitting".
– Benjamin W.
Nov 14 '18 at 5:52
add a comment |
1
Bash allows you to use$(< "$filename"), which is a little bit faster than usingcat. Also, the key mechanic that quotes suppress in this case is "word splitting".
– Benjamin W.
Nov 14 '18 at 5:52
1
1
Bash allows you to use
$(< "$filename"), which is a little bit faster than using cat. Also, the key mechanic that quotes suppress in this case is "word splitting".– Benjamin W.
Nov 14 '18 at 5:52
Bash allows you to use
$(< "$filename"), which is a little bit faster than using cat. Also, the key mechanic that quotes suppress in this case is "word splitting".– Benjamin W.
Nov 14 '18 at 5:52
add a comment |
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While not solving your immediate issue, is there any reason you are using command line arguments instead of reading standard input?
– Mad Physicist
Nov 14 '18 at 5:09
1
Why don't you read file in program rather than passing it as an argument. Let's say your file location is dynamic you could pass it then. Think about that if file is very big then it may cause slowness to your program.
– RavinderSingh13
Nov 14 '18 at 5:10
Those are both great suggestions, and I'll probably implement those changes soon. I only posted this question to share the fix I found in case anyone else was in a situation where they couldn't modify the program in question. I'd definitely advocate posting those as answers too!
– Daniel
Nov 14 '18 at 5:26