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Top Forums Shell Programming and Scripting Send Foreground job to background redirecting output Post 302403081 by Corona688 on Thursday 11th of March 2010 10:41:10 AM
Old 03-11-2010
Quote:
Originally Posted by jhullbuzz
@corona688 ok so it creates the output at the initial process call. what if i were to start it in the background with a logfile...is there a way to bring it into the FG?
I repeat: The shell cannot redirect output for a process that already exists. You can't just reach in and change a completely different process' file table for it.

The shell has to do all redirection for a new process before the new process is run -- it does this by creating a subshell, which does all redirection, then replaces itself with the new program but keeping I/O redirections intact. Once that's done, the new process controls its own output like any other program.

If you want to view the logfile as its written to, try 'tail -f logfile'. This will watch logfile for new lines and print them to standard output.

There's also the screen terminal/utility/shell/thing, which uses network sockets to do something similar to you want. It keeps sessions that you can connect and disconnect to without killing or halting them.
 

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LOGSAVE(8)                                                    System Manager's Manual                                                   LOGSAVE(8)

NAME
logsave - save the output of a command in a logfile SYNOPSIS
logsave [ -asv ] logfile cmd_prog [ ... ] DESCRIPTION
The logsave program will execute cmd_prog with the specified argument(s), and save a copy of its output to logfile. If the containing directory for logfile does not exist, logsave will accumulate the output in memory until it can be written out. A copy of the output will also be written to standard output. If cmd_prog is a single hyphen ('-'), then instead of executing a program, logsave will take its input from standard input and save it in logfile logsave is useful for saving the output of initial boot scripts until the /var partition is mounted, so the output can be written to /var/log. OPTIONS
-a This option will cause the output to be appended to logfile, instead of replacing its current contents. -s This option will cause logsave to skip writing to the log file text which is bracketed with a control-A (ASCII 001 or Start of Header) and control-B (ASCII 002 or Start of Text). This allows progress bar information to be visible to the user on the console, while not being written to the log file. -v This option will make logsave to be more verbose in its output to the user. AUTHOR
Theodore Ts'o (tytso@mit.edu) SEE ALSO
fsck(8) E2fsprogs version 1.44.1 March 2018 LOGSAVE(8)
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