UNIX - Mac OS X Hints

Save all of your Terminal activity to a file

May 11, '12 07:30:00AM • Contributed by: chrisgerke

I use Terminal everyday, and I find it a good idea to log everything I you. It makes it much easier to undo your mistakes when you know what those mistakes were. Here's how I do this:

Open Terminal's preferences.

Go to Settings, then Shell. You can choose here to run a command at startup. You could create a simple log of your session using the following:

/usr/bin/script ~/Desktop/Terminal.log

This will log everything you do and append it to the log file.

I like to keep my history so instead I wrote this small script that archives previous sessions by renaming the file with a date/time string. I then set Terminal.app to run at startup the following command:

~/Desktop/logger.sh

Here's the script:

#!/bin/bash
# logger.sh
# Log everything you do in Terminal.

#* Formatted date & time string.
FORMATTED_DATE=`/bin/date "+%Y-%m-%d%H%M%S"`

#* Archive the previous file
/bin/cp -f ~/Desktop/Terminal.log{,.&#36;FORMATTED_DATE.txt}

#* Begin a new one
/usr/bin/script ~/Desktop/Terminal.log

[kirkmc adds: This is a good idea. I don't use Terminal a lot, but I find that I sometimes need to remember a command I ran in the past which is no longer in my history.

Also, this is similar to something I do with texts I write. I do most of my writing in BBEdit, and I have a number of "scratch" files which I change every year. For example, I have one file for most of what I write, another just for Mac OS X Hints, and another for a specific client I write for. I archive these files at the end of the year, and create new ones. If I ever need to go back to these files to look for something I can do so. I don't bother to enter dates - which I could do easily enough with a TypeIt4Me shortcut - but if I'm looking for something I'll generally know what text to search for.]

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Automatically restart network on lost connection

Apr 17, '12 07:30:00AM • Contributed by: desepticon

Often times, for whatever reason, the Internet connection on my Mac will lock up. Only restarting the Airport or Ethernet interfaces seem to resolve the issue in a timely manner. (This is different from a router crash which requires a manual restart of the router - in my case an Airport Extreme.) I have developed some interconnected scripts that will automatically accomplish this task for me when attached to launchctl. This is important for me because I often have to access files over the internet and if the connection has locked up there is no way for me to access them without manual intervention.

The first script gets the active network interface. This is called by the second script which determines whether to run a matched script for either the Ethernet or AirPort interfaces. These third and fourth scripts restart either the Ethernet or AirPort connection respectively. These last two scripts can also be configured to send you an e-mail if this happens by altering the 'tobenotified" string to reflect your e-mail address in each of them. Be sure to maintain the single quotes. Or, if you do not wish to receive e-mail, comment these parts out.

Name the first script "active_interface.sh", and the second "check_internet_master.sh". This second script is what controls the rest. Attach it to lauchctl to do this automatically and never worry about a lost connection. The third and fourth scripts should be called "check_internet.sh" and "check_internet2.sh". Of course you can always name these whatever you want, but be sure to put the path to them in the scripts. Make sure to chmod all the files executable; and, unless the scripts are altered, they should also be run from the same folder.

In order for ifconfig to run with out intervention, the script needs to be run as root. Alternatively, you could make an exception for ifconfig in your /etc/sudoers file by adding the line (if you run as admin - else put %users):

%admin    ALL= NOPASSWD: /sbin/ifconfig

I don't think this is too much of a security issue.

With this setup, I find I am nearly impervious to lost connections.

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Automatically reclaim memory from leaky programs

Apr 11, '12 07:30:00AM • Contributed by: desepticon

Sometimes applications have a nasty habit of claiming a lot of memory and never releasing it back to the system. Over time, this can cause affect performance. Most of the time, this can simply be fixed by quitting and restarting the offending program, but I wanted to find a more elegant solution.

After searching the Internet, I found few scripts that I could tweak to achieve what I wanted. Heres what I came up with. The first script is a python script I found at StackExchange by user drfrogsplat that gets information about system memory. The second is a bash script I wrote that runs the purge command if you have over a certain amount of inactive memory, in my case 500MB (probably overkill). Note that I think you need developer tools installed to use the purge command. There's probably an easier way to do this with vm_stat directly but I'm not good enough at awk/grep/sed to it figure out.

The bash script can be attached to a launchd plist to run automatically at certain intervals or whenever you want. I seems to work pretty well for me.

#!/usr/bin/python

import subprocess
import re

# Get process info
ps = subprocess.Popen(['ps', '-caxm', '-orss,comm'], stdout=subprocess.PIPE).communicate()[0]
vm = subprocess.Popen(['vm_stat'], stdout=subprocess.PIPE).communicate()[0]

# Iterate processes
processLines = ps.split('\n')
sep = re.compile('[\s]+')
rssTotal = 0 # kB
for row in range(1,len(processLines)):
   rowText = processLines[row].strip()
   rowElements = sep.split(rowText)
   try:
       rss = float(rowElements[0]) * 1024
   except:
       rss = 0 # ignore...
   rssTotal += rss

# Process vm_stat
vmLines = vm.split('\n')
sep = re.compile(':[\s]+')
vmStats = {}
for row in range(1,len(vmLines)-2):
   rowText = vmLines[row].strip()
   rowElements = sep.split(rowText)
   vmStats[(rowElements[0])] = int(rowElements[1].strip('\.')) * 4096

print 'Wired Memory:\t\t%d MB' % ( vmStats["Pages wired down"]/1024/1024 )
print 'Active Memory:\t\t%d MB' % ( vmStats["Pages active"]/1024/1024 )
print 'Inactive Memory:\t%d MB' % ( vmStats["Pages inactive"]/1024/1024 )
print 'Free Memory:\t\t%d MB' % ( vmStats["Pages free"]/1024/1024 )
print 'Real Mem Total (ps):\t%.3f MB' % ( rssTotal/1024/1024 )

==============================================================
==============================================================

#!/bin/bash

MM=`/Path/to/python/script.py | awk '/Inactive/ {print $3}'`

echo "Testing status of inactive free memory..."

if [ "$MM" -gt "500" ]; then
    echo "You have too much inactive free memory." $MM"MB Releasing now..."
    purge
    exit 0
else
    echo "Memory ammount" $MM"MB does not meet purge threshold."
    exit 0
fi

[kirkmc adds: I'm guessing that this will be controversial. There seem to be dozens of apps on the Mac App Store that free up memory, and I'm not convinced that this is necessary. The only time I would see this as being essential is if that inactive memory is leading to more paging. Lately, I've been amazed at how little paging my Mac mini does; with 8 GB RAM, it rarely uses more than one swap file, and this with an uptime of several days.

I think that, in most cases, if you encounter an issue with memory, it's just as simple to use the purge command in Terminal. And, yes, I do see certain applications and processes taking up a lot of memory, notably iTunes and WebProcess. But note that the purge command doesn't free up all inactive memory anyway.

And, can someone confirm that Xcode is needed to have the purge command? Mine is in /usr/bin, and I don't think Xcode installs anything there, at least any more, now that it gets put in /Applications.]

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