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readandwrite

readandwrite(command)

Starts running a command asynchronously, and returns a tuple (stdout,stdin,process) of the output stream and input stream of the process, and the process object itself.

Examples

1. Run a command and capture output streams:

   julia> cmd = `ls -al`;
   julia> stdout, stdin, proc = readandwrite(cmd);
   julia> read(stdout, String)
   "total 8\n-rw-r--r--  1 user  staff   456 Sep 10 11:30 file1.txt\n-rw-r--r--  1 user  staff   789 Sep 10 11:30 file2.txt\n"

   This example runs the command ls -al asynchronously and captures its stdout using read function.

2. Interact with the process using stdin:

   julia> cmd = `grep "hello"`;
   julia> stdout, stdin, proc = readandwrite(cmd);
   julia> write(stdin, "Hello, world!\n");
   julia> close(stdin);
   julia> read(stdout, String)
   "Hello, world!\n"

   In this example, the command grep "hello" is started asynchronously, and we interact with the process by writing to its stdin using the write function.

3. Capture both stdout and stderr:

   julia> cmd = `ls non_existent_file`;
   julia> stdout, stdin, proc = readandwrite(cmd);
   julia> read(stdout, String)
   "ls: non_existent_file: No such file or directory\n"

   Here, the command ls non_existent_file is run, and both stdout and stderr are captured in the stdout stream.

Common mistake example:

julia> cmd = `non_existing_command`;
julia> stdout, stdin, proc = readandwrite(cmd)
ERROR: IOError: could not spawn `non_existing_command`: no such file or directory (ENOENT)

In this example, the command non_existing_command does not exist, resulting in an IOError. It's important to make sure that the command provided is valid and exists on the system.

See Also

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