I wrote previously a how-to to set your iTerm tab title.

I finally found a tool to do the same thing with the default Mac OS X Terminal.

Check it out here, it works perfectly for me!  link is dead.

On my Mac OS X 10.6.6 and bash (3.2.48(1)-release), you can set your tab title with the PROMPT_COMMAND variable as follow:

export PROMPT_COMMAND=’echo -ne “\033]0;${USER}@${HOSTNAME%%.*}\007″‘

Add this to your .bashrc or /etc/profile file and you’re done

Playing with memory_limit in PHP, we wanted to know the average memory usage per php-cgi process. This is easily calculated with our best friend awk.

First, get the number of php running processes:

# ps aux | grep php-cgi | grep -v grep | wc -l
126

Then, use awk to calculate the average memory usage for these processes:

# ps aux | grep --exclude=grep php-cgi | grep -v grep | awk 'BEGIN{s=0;}{s=s+$6;}END{print s/126;}'
33987.8

The number used in the calculation is the field RSS given by ps. The ps manual page says:

rss: resident set size, the non-swapped physical memory that a task has used (in kiloBytes)

You can also calculate the total memory used by all php-cgi processes:

# ps aux | grep --exclude=grep php-cgi | grep -v grep | awk 'BEGIN{s=0;}{s=s+$6;}END{print s;}'
4302028

If you need to watch the trend of this average memory usage, a little shell loop does the trick:

# while [ 1 ]; do ps aux | grep --exclude=grep php-cgi | grep -v grep | awk 'BEGIN{s=0;}{s=s+$6;}END{print s/126;}'; sleep 2; done
34401.3
34405.1
34408.4
34409.4
34414.2
34417

This command is used to update the access and modification times of files.

• touch’s syntax

touch [option] file_name(s)
touch file1 file2 file3

• Here some examples:

# touch /tmp/file
# ls -l /tmp/file
rw-r--r-- 1 charlybr charlybr 0 Sep 10 16:13 /tmp/file

• Update access and modification time to current time:

# ls -l /tmp/file
rw-r--r-- 1 charlybr charlybr 0 Sep 10 16:13 /tmp/file
# touch /tmp/file
# ls -l /tmp/file
rw-r--r-- 1 charlybr charlybr 0 Sep 10 16:14 /tmp/file

• Update access and modification time to a specified timestamp ([[CC]YY]MMDDhhmm[.ss] format):

# touch -t 09091842 /tmp/file
# ls -l /tmp/file
-rw-r--r-- 1 charlybr charlybr 0 Sep  9 18:42 /tmp/file

• Update access and modification time to a specified date

# touch -d '9 Sep' /tmp/file
# ls -l /tmp/file
-rw-r--r-- 1 charlybr charlybr 0 Sep  9 00:00 /tmp/file
# touch -d '9 Sep 2008 13:14' /tmp/file
# ls -l /tmp/file
-rw-r--r-- 1 charlybr charlybr 0 Sep  9 13:14 /tmp/file

Links

• touch is part of the Coreutils package
• touch documentation page
• man page on FreeBSD

Macports binaries are installed in /opt/local/bin, so you just need to add this path to your PATH environment variable. Example with your user, add to your $HOME/.profile :

export PATH=$PATH:/opt/local/bin

You can source your profile file to update your environment:

$ source .profile

You are now able to use the port command:

$ sudo port -v selfupdate