this bash logger is part of http://github.com/RichardBronosky/tools/blob/master/bash.patterns/

bash.log.sh

# sample output can be found at http://gist.github.com/550332#file_bash.log.sh.log
LOGFILE=/tmp/${0##*/}.log

# a general purpose logging function that is used as prefix similar to time see: man time
log(){
    (printf \#%.0s {1..50}; echo)>> $LOGFILE
    if [[ $1 == '-s' ]];then
        shift
        echo -e "$*" >> $LOGFILE
        return 0
    fi
    if [[ -t 0 ]]; then
        echo $* >> $LOGFILE
        $* 2>&1 | tee -a $LOGFILE
    else
        $* << EOF 2>&1 | tee -a $LOGFILE
$(echo "$* << FROM_STDIN" >> $LOGFILE; tee -a $LOGFILE; echo "FROM_STDIN" >> $LOGFILE)
EOF
    fi
}

# a function for demoing
my_func(){
    echo $* to standard out > /dev/stdout
    echo to standard error > /dev/stderr
}

# truncate the file
echo -n >$LOGFILE

# log a string
log -s "starting a\nnew log..."

# log a simple command
log date

# log a complex command (`du` prefixed with `time` prefixed with `log`) that will [likely] encounter permissions errors
log time du -sh /etc/

# log a function call with arguments
log my_func alfa bravo charlie

# log a pipe
cat /etc/hosts | log wc

# log a redirect
log wc < /etc/hosts

# log a heredoc
log wc << EOF
Acknowledgments:
    Copyright (c) 2010 Richard Bronosky
    Offered under the terms of the MIT License.
    http://www.opensource.org/licenses/mit-license.php
    Created while employed by CMGdigital
EOF

# show the result
echo -e "\n\n########## LOG CONTENTS ##########\n"
cat $LOGFILE

bash.log.sh.log

##################################################
starting a
new log...
##################################################
date
Wed Aug 25 23:15:19 EDT 2010
##################################################
time du -sh /etc/
du: /etc//cups/certs: Permission denied
1.1M	/etc/
        0.00 real         0.00 user         0.00 sys
##################################################
my_func alfa bravo charlie
alfa bravo charlie to standard out
to standard error
##################################################
wc << FROM_STDIN
127.0.0.1       localhost
255.255.255.255 broadcasthost
::1             localhost
fe80::1%lo0     localhost

127.0.0.1 signin.example.com
127.0.0.1 www.example.com
127.0.0.1 example.com
FROM_STDIN
       8      14     186
##################################################
wc << FROM_STDIN
127.0.0.1       localhost
255.255.255.255 broadcasthost
::1             localhost
fe80::1%lo0     localhost

127.0.0.1 signin.example.com
127.0.0.1 www.example.com
127.0.0.1 example.com
FROM_STDIN
       8      14     186
##################################################
wc << FROM_STDIN
Acknowledgments:
    Copyright (c) 2010 Richard Bronosky
    Offered under the terms of the MIT License.
    http://www.opensource.org/licenses/mit-license.php
    Created while employed by CMGdigital
FROM_STDIN
       5      20     201

command output

Wed Aug 25 23:15:19 EDT 2010
du: /etc//cups/certs: Permission denied
1.1M	/etc/
        0.00 real         0.00 user         0.00 sys
alfa bravo charlie to standard out
to standard error
       8      14     186
       8      14     186
       5      20     201


########## LOG CONTENTS ##########

##################################################
starting a
new log...
##################################################
date
Wed Aug 25 23:15:19 EDT 2010
##################################################
time du -sh /etc/
du: /etc//cups/certs: Permission denied
1.1M	/etc/
        0.00 real         0.00 user         0.00 sys
##################################################
my_func alfa bravo charlie
alfa bravo charlie to standard out
to standard error
##################################################
wc << FROM_STDIN
127.0.0.1       localhost
255.255.255.255 broadcasthost
::1             localhost
fe80::1%lo0     localhost

127.0.0.1 signin.example.com
127.0.0.1 www.example.com
127.0.0.1 example.com
FROM_STDIN
       8      14     186
##################################################
wc << FROM_STDIN
127.0.0.1       localhost
255.255.255.255 broadcasthost
::1             localhost
fe80::1%lo0     localhost

127.0.0.1 signin.example.com
127.0.0.1 www.example.com
127.0.0.1 example.com
FROM_STDIN
       8      14     186
##################################################
wc << FROM_STDIN
Acknowledgments:
    Copyright (c) 2010 Richard Bronosky
    Offered under the terms of the MIT License.
    http://www.opensource.org/licenses/mit-license.php
    Created while employed by CMGdigital
FROM_STDIN
       5      20     201