Restoring stdout and stderr to default value

问题

In shell script, We can change the default input to a File using the exec command as follow :

  exec 1>outputfile

However, if in the same script if I want to restore the stdout descriptor '1' to the default (terminal). How can we achieve that?

回答1:

This example

Example 20-2. Redirecting stdout using exec

#!/bin/bash
# reassign-stdout.sh

LOGFILE=logfile.txt

exec 6>&1           # Link file descriptor #6 with stdout.
                    # Saves stdout.

exec > $LOGFILE     # stdout replaced with file "logfile.txt".

# ----------------------------------------------------------- #
# All output from commands in this block sent to file $LOGFILE.

echo -n "Logfile: "
date
echo "-------------------------------------"
echo

echo "Output of \"ls -al\" command"
echo
ls -al
echo; echo
echo "Output of \"df\" command"
echo
df

# ----------------------------------------------------------- #

exec 1>&6 6>&-      # Restore stdout and close file descriptor #6.

echo
echo "== stdout now restored to default == "
echo
ls -al
echo

exit 0

appears to show what you want. It came from the ABS, where there is a small amount of discussion and other relevant information.

回答2:

Try the "tee" command:

exec | tee outputfile

Look at the tee manpage for more explainations:

tee - read from standard input and write to standard output and files

来源：https://stackoverflow.com/questions/21106465/restoring-stdout-and-stderr-to-default-value