showConnections             package:base             R Documentation

_D_i_s_p_l_a_y _C_o_n_n_e_c_t_i_o_n_s

_D_e_s_c_r_i_p_t_i_o_n:

     Display aspects of connections.

_U_s_a_g_e:

     showConnections(all=FALSE)
     getConnection(what)
     closeAllConnections()

     stdin()
     stdout()
     stderr()

_A_r_g_u_m_e_n_t_s:

     all: logical: if true all connections, including closed ones and
          the standard ones are displayed. If false only open
          user-created connections are included.

    what: integer: a row number of the table given by
          `showConnections'.

_D_e_t_a_i_l_s:

     `stdin()', `stdout()' and `stderr()' are standard connections
     corresponding to input, output and error on the console
     respectively (and not necessarily to file streams).  They are
     text-mode connections of class `"terminal"' which cannot be opened
     or closed, and are read-only, write-only and write-only
     respectively. The `stdout()' connection can be re-directed by
     `sink'.

     `showConnections' returns a matrix of information.  If a
     connection object has been lost or forgotten, `getConnection' will
     take a row number from the table and return a connection object
     for that connection, which can be used to close the connection,
     for example.

     `closeAllConnections' closes all open user connections.

_V_a_l_u_e:

     `stdin()', `stdout()' and `stderr()' return connection objects.

     `showConnections' returns a character matrix of information with a
     row for each connection, by default only for open non-standard
     connections.

     `getConnection' returns a connection object, or `NULL'.

_S_e_e _A_l_s_o:

     `connection'

_E_x_a_m_p_l_e_s:

     showConnections(all = TRUE)

     textConnection(letters)
     # oops, I forgot to record that one
     showConnections()
     #  class     description      mode text   isopen   can read can write
     #3 "letters" "textConnection" "r"  "text" "opened" "yes"    "no"     
     close(getConnection(3))
     showConnections()

