What is special about dev tty

Question

ls -la  dev tty shows the output   crw-rw-rw- 1 root tty 5  0 Dec 14 22 21  dev tty   What does c at the beginning mean  When I do something like pwd  gt   dev tty it prints to the stdout  What does the file  dev tty contain

User · Answer

The  c  means it s a character special file

User · Answer

The  c  means it s a character device  tty is a special file representing the  controlling terminal  for the current process   Character Devices  Unix supports  device files   which aren t really files at all  but file-like access points to hardware devices  A  character  device is one which is interfaced byte-by-byte  as opposed to buffered IO    TTY   dev tty is a special file  representing the terminal for the current process  So  when you echo 1  gt   dev tty  your message   1   will appear on your screen  Likewise  when you cat  dev tty  your subsequent input gets duplicated  until you press Ctrl-C     dev tty doesn t  contain  anything as such  but you can read from it and write to it  for what it s worth   I can t think of a good use for it  but there are similar files which are very useful for simple IO operations  e g   dev ttyS0 is normally your serial port   This quote is from http   tldp org HOWTO Text-Terminal-HOWTO-7 html ss7 3        dev tty stands for the controlling terminal  if any  for the current   process   To find out which tty s are attached to which processes use   the  ps -a  command at the shell prompt  command line   Look at the    tty  column  For the shell process you re in   dev tty is the   terminal you are now using  Type  tty  at the shell prompt to see what   it is  see manual pg  tty 1     dev tty is something like a link to   the actually terminal device name with some additional features for   C-programmers  see the manual page tty 4     Here is the man page  http   linux die net man 4 tty

User · Answer

dev tty is a synonym for the controlling terminal  if any  of the current process   As jtl999 says  it s a character special file  that s what the c in the ls -l output means   man 4 tty or man -s 4 tty should give you more information  or you can read the man page online here   Incidentally  pwd  gt   dev tty doesn t necessarily print to the shell s stdout  though it is the pwd command s standard output    If the shell s standard output has been redirected to something other than the terminal   dev tty still refers to the terminal   You can also read from  dev tty  which will normally read from the keyboard

[unix] What is special about /dev/tty?

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