5 ms·

While I'm doing command line file sharing, why not just directly transfer a file to my peer with netcat? Server: $ cat hugefile.ext | nc -l -p 9999 Clien

by yuvadam 12y ago

While I'm doing command line file sharing, why not just directly transfer a file to my peer with netcat? Server: $ cat hugefile.ext | nc -l -p 9999 Client: $ nc server.ip 9999 > hugefile.ext We tend to forget how the network is built, and how easy it is to use it with the right tools.

klapinat0r 12y ago
While I do agree with you, I think a common "gotcha" is in dealing with port forwards and firewalls.
- yuvadam 12y ago
  Of course, NATs will break this type of scenario, but that can easily be solved with SSH tunneling into an accessible server.
  - StavrosK 12y ago
    Reverse tunnelling is more useful for this sort of scenario. Then the other person can connect to the remote server port and it'll reach you.
xorcist 12y ago
Ah, a candidate for the useless use of cat award. The first command can be given more easily as: nc -l -p 9999 < hugefile.ext (which also mirrors the logic of the second, modulo nc's idiosyncratic argument syntax)
- unfamiliar 12y ago
  The cat version much more clearly represents the flow of data. We read left to right, it makes no sense to me to have data flow written right to left (and only for input files, while output files read left to right). When building commands up from basics, it makes much more sense to start with cat. I will typically cat the file to see it's contents, then modify the command with a pipe to another program, and make keep adding processing steps to the end of the pipeline. Your < inputfile.txt notation completely breaks this model. Just because you read something on a webpage that one time doesn't mean it is the one true way.
  - xorcist 12y ago
    No, it makes much more sense to start with the command that is to process the file. Most commands take a command line argument to specify which file to process. This mirrors the redirection syntax perfectly: You say: grep haystack needle.txt or: grep haystack < needle.txt whereas this is more convoluted: cat needle.txt | grep haystack As a bonus the syntax looks the same for output redirection: sort < infile.txt > outfile.txt whereas this is not as readable: cat infile.txt | sort > outfile.txt What "makes sense" to you doesn't always to other people. In this case it's trivial, but it's a nightmare to debug larger scripts when there are lots of unnecessary redirections and if statements. Shell scripts may be one-offs, but they tend to linger. It's not unwise to spend a few extra moments to make them readable and follow best practice. It is code after all. (Also; a bit silly with the personal attacks.)
rakoo 12y ago
How do you identify a particular file ? Also, HTTP is more accessible than raw TCP (you can use it from the browser)

by yuvadam 12y ago

klapinat0r 12y ago

While I do agree with you, I think a common "gotcha" is in dealing with port forwards and firewalls.

yuvadam 12y ago
Of course, NATs will break this type of scenario, but that can easily be solved with SSH tunneling into an accessible server.
- StavrosK 12y ago
  Reverse tunnelling is more useful for this sort of scenario. Then the other person can connect to the remote server port and it'll reach you.

xorcist 12y ago

Ah, a candidate for the useless use of cat award. The first command can be given more easily as: nc -l -p 9999 < hugefile.ext (which also mirrors the logic of the second, modulo nc's idiosyncratic argument syntax)

unfamiliar 12y ago
The cat version much more clearly represents the flow of data. We read left to right, it makes no sense to me to have data flow written right to left (and only for input files, while output files read left to right). When building commands up from basics, it makes much more sense to start with cat. I will typically cat the file to see it's contents, then modify the command with a pipe to another program, and make keep adding processing steps to the end of the pipeline. Your < inputfile.txt notation completely breaks this model. Just because you read something on a webpage that one time doesn't mean it is the one true way.
- xorcist 12y ago
  No, it makes much more sense to start with the command that is to process the file. Most commands take a command line argument to specify which file to process. This mirrors the redirection syntax perfectly: You say: grep haystack needle.txt or: grep haystack < needle.txt whereas this is more convoluted: cat needle.txt | grep haystack As a bonus the syntax looks the same for output redirection: sort < infile.txt > outfile.txt whereas this is not as readable: cat infile.txt | sort > outfile.txt What "makes sense" to you doesn't always to other people. In this case it's trivial, but it's a nightmare to debug larger scripts when there are lots of unnecessary redirections and if statements. Shell scripts may be one-offs, but they tend to linger. It's not unwise to spend a few extra moments to make them readable and follow best practice. It is code after all. (Also; a bit silly with the personal attacks.)

rakoo 12y ago

How do you identify a particular file ? Also, HTTP is more accessible than raw TCP (you can use it from the browser)