OSXFAQ Mac OS X UNIX Tip-of-the-Day  

Week 104 - Unix Commands Reference IV (11 April 2005)

by Adrian Mayo - Editor, OSXFAQ

Friday - Example Usage

These examples are taken from my own notes and have not been tested for a while.

Screen Capture Command

When you use the interactive version (command-shift-4), the space bar will toggle between the regular marquee selection mode and a new mode to capture just a single window, the Dock or the menu bar. The cursor changes to a camera icon when you are in this new mode and as you mouse over different areas of the screen the screen capture target is highlighted for you.

Screen captures can be triggered from the command line (and therefore AppleScript, perl, etc.) using the new screencapture command found in /usr/sbin/

usage: screencapture [-icmwsWx] [file] [cursor]
-i capture screen interactively, by selection or window
control key - causes screen shot to go to clipboard
space key - toggle between mouse selection and window selection modes
escape key - cancels interactive screen shot
-c force screen capture to go to the clipboard
-m only capture the main monitor, undefined if -i is set
-w only allow window selection mode
-s only allow mouse selection mode
-W start interaction in window selection mode
-x do not play sounds file where to save the screen capture

hdiutil Command

Here is how to create a 50MB drive image, backup data to it, and then burn it onto a CD (directly in the commandline).

hdiutil create -fs HFS+ -volname Backup -size 50m ~/Desktop/backup.dmg
hdiutil mount ~/Desktop/backup.dmg
ditto -rsrc -V ~/Desktop/datatobackup /Volumes/Backup >> /Volumes/Backup/backup.log
hdiutil unmount /Volumes/Backup
hdiutil burn ~/Desktop/backup.dmg -noverifyburn -noeject

NetInfo Command Set

- Backup a NetInfo database
nidump -r / -t localhost/local > backup.nidump

- Restore a NetInfo database from backup
periodic daily backs-up the NI database to /var/backups/local.nidump

From single user with / mounted rw, move old /var/db/netinfo/local.nidb
Start essential services
/usr/libexec/kextd
/usr/sbin/configd
/sbin/SystemStarter

Create blank NetInfo database and start NetInfo
/usr/libexec/create_nidb
/usr/sbin/netinfod -s local

Load the backup into NetInfo:
/usr/bin/niload -d -r / . < /var/backups/local.nidump

- Re-create NetInfo via OS X first-time setup
rm /var/db/.AppleSetupDone
reboot

Other Commands

bless
Set OS X as a startup
sudo bless -folder '/System/Library/CoreServices' -setOF
Set OS 9 as a startup
sudo bless -folder9 '/Volumes/Mac OS 9/System Folder' -setOF

defaults
defaults read/write/delete <file> <parameters>
defaults write com.apple.terminal TerminalOpaqueness '0.85';

fsck
In single user mode, to repair HFS disc 1 partition 5
fsck_hfs -y /dev/rdisk1s5

man
man 7 ascii ... ASCII table
man 7 hier ... file system hierarchy
man cmd | col -b ... print manual pages

mount
mount_afp [-o option1[,option2 ...]] afp://[username:password]@rhost[:port]/volume node

mount_cd9660 /dev/disk2s1 /Volumes/cd
umount /Volumes/cd

mount -t hfs -w /dev/disk0s10 /Volumes/Grima

nvram
nvram -p ... to print variables
sudo nvram boot-args="-v" ... set verbose mode on boot

tcpflow
sudo tcpflow -i en1 -c port 80

whois
whois -h whois.arin.net ip-address

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