Distilled Wisdom

Frequently, I find myself doing something (or rather, trying to do something) which I know is not particularly difficult, but I can't remember the specifics of how to do it. It could be redirecting STDERR from a command under bash, changing settings on my camera, or making MS Word behave the way I want it to.

So at some point, I began keeping a hierarchical collection of notes to remind myself how to do stuff. I call it my distilled wisdom. None of it's particularly profound. In fact, some of it's downright obscure ... useless to anyone in the world ... except for that one person who can't remember or doesn't know a given detail.

• Unix

  • Ethernet Devices:

    MacOSX: en0
    Linux: eth0
    OpenBSD: dc0

  • Crontab format:

    minute hour day-of-month month day-of-week command e.g.,

    0 * * * * bin/whatever.bash > log 2>&1
    1 1 * * * (cd /blah; ./blah) > /dev/null 2>&1 
    

    Remember, it runs under /bin/sh, not whatever your personal default shell may be!

  • PostgreSQL

    to start postmaster, use

    pg_ctl start
    

    (has many options), e.g. -o -i to enable network connections

  • Shell Stuff

    • Crypt password for apache .htaccess files

      perl -e "print crypt('password','xX').'\n';"
      

      where xX is the salt. Of course, you could just use the Apache htpasswd command.
    • Bash loops:

      for i in *.java; do echo $i; done
      
      for i in *.java; do
      mv $i ${i%java}new_ext
      done
      

      (be sure not to quote the string to be expanded)

      example: rename file000-t.jpg to thumb_file000.jpg:

      for i in file*.jpg; do mv $i thumb_${i/-t/}; done
      

    • Bash loops using C syntax:

      for ((i=0;i<10;i++)); do echo $i; done
      
      ((i=o)); while ((i<10)); do echo $i; ((i += 1)); done
      

    • redirection examples (stdout & stderr to filespec):

      bash: (cmd) 2>&1 | tee filespec

      csh: (cmd) |& tee filespec

    • multiple items in bash:

      ls ab[c,d]

    • c shell list processing:

      for f (*.conf) do
        set b=`echo $f | sed 's/\(.*\).conf/\1/'`
        echo $b
      

  • Find/Piping tricks:

    find . -mtime -1 | tar -czf - -T - | ssh host1 cat > file.tar.gz
    

    (finds files changed in last 24 hours, compress into tar stream, write tar file on host1)

    find . -mtime -1 | tar -czf - -T - | ssh host1 tar -xvf -
    

    (finds files changed in last 24 hours, compress into tar stream, copy files to host1)

    tar czvf - dirname | ssh host1 "cat - > dirname.tar.gz"
    

    (tars a directory onto a remote machine)

  • File Mungeing tricks:

    Exclude all lines from file1 that exist in file2 (e.g., remove a list of email addresses from a larger list):

    sort -u file1 > file1s
    sort -u file2 > file2s
    comm -2 -3 file1s file2s
    

  • ssh tunnel tricks:

    (also see shell stuff)

    ssh tunneling:

    ssh -g -L localport:localhost:remoteport user@remotehost
    

    (connect port "localport" on localhost to port "remoteport" on remotehost... Now "telnet localhost localport" will go to remote host's remoteport)

    ssh -L localport:remotehost:remoteport user@originatehost
    

    (creates a tunnel from localhost:localport to remotehost:remoteport, which will behave as if originating from originatehost.)

  • Find stuff:

    find . -name "*.html" -exec grep -il page {} \;
    

    (grep all html files for the word "page" without regard to case)

    find . \( -iname "*.gif" -o -iname "*.jpg" \)
    

    (case insensitive find of jpg or gif files)

    find -name '_most_recent' -prune , ! -name '_most_recent' -mtime -1 -ctime -1 -type d -print
    

    (Display any directories have been created or modified in the last day, excluding the dircetory named "_most_recent".)

• Debian

  • update versions:

    apt-get update
    apt-get -u dist-upgrade
    

• HylaFax

  • after restarting, remember to re-run faxmodem:

    /etc/init.d/hylafax stop
    /etc/init.d/hylafax start
    /usr/local/sbin/faxmodem ttyS4
    

  • sendfax -h password:

    for sendfax -h flag to work w/out asking for password, put host in hylafax/etc/hosts.hfaxd

• Oracle

  • query open sessions:

    select * from v$session
    

    (or, depending on Oracle version, v_$session)

  • starting Oracle:

    lsnrctl
      start
      exit
    
    svrmgrl
      connect internal
      startup
      exit
    

  • Functional Index permissions

    permission required for creating functional index: query rewrite

    grant query rewrite to (account)
    

  • get table or view definition:

    desc[ribe] [table or view name]
    

  • piping script into sql*plus:

    sqlplus user/pass @scriptname
    

  • describe tablespaces:

    select * from v_$datafile
    select * from USER_FREE_SPACE
    

  • Oracle archives:

    describe archive mode:

    archive log list
    

    enable or disable archiving:

    alter system archive log (start/stop)
    

• Nikon N80

  • Batteries:

    2 x CR123A
    2 x DL123A

  • Custom Functions:

    
    1 - auto rewind at end of roll (<0>=active)
    2 - reset to DX speed setting for new rolls (<0>=active)
    3 - bracketing order (0 = meter,under,over <1> = under,meter,over)
    4 - grid display (0 = off, <1>)
    5 - illumination for grid line superimposition (<0> = auto/low light, 1 = never, 2 = always)
    6 - focus area selection (<0> = normal selection, 1 = successive rotation of focus area selection)
    7 - auto exposure lock when shutter release lightly pressed (0 = disabled, <1>)
    8 - auto film loading when camera back closed (<0> = enabled)
    9 - closest subject priority dynamic AF in single servo AF (<0> = enabled)
    10 - closest subject priority dynamic AF in continuous servo AF (<0> = disabled)
    11 - AE-L/AF-L button (0 = AE/AF simultaneous lock, <1> = AE lock only, 2 = AF lock only, 3 = AE lock until pressed again, 4 = AF only starts by pushing AE-L/AF-L button)
    12 - command dials (<0> = front->aperture, back->shutter speed, 1 = front->shutter speed back->aperture)
    13 - film rewind (<0> = fast, 1 = quiet)
    14 - multiple exposure (<0> = single shutter release operation, 1 = continuous shutter release operation)
    15 - time delay for meter auto shutoff (number of seconds <6>)
    16 - self timer duration (number of seconds <10>)
    17 - LCD illuminate on button push (<0> = disabled)
    18 - AF assist illuminator (<0> = active)

• Digisnap 2000

  • Timelapse with Coolpix

    1. set camera up as appropriate (manual focus @ infinity, VGA, Auto Exosure lock etc.)
    2. leave camera on
    3. plug digisnap into camera
    4. activate by clicking single shot for 1/2 sec: digisnap will flash yellow, then a few seconds later green
    5. push timelapse button to initiate seq.
    
    If it's working, it will flash green every four seconds

  • to change interval in the field:

    1. stop sequence by hitting timelapse
    2. hold down timelapse - it will flash seconds in yellow.
    3. Release when sequence is correct length
    4. push timelapse button to initiate seq.
    
    If it's working, it will flash green every four seconds

• Ceramics

  • Long Beach Blend shrinkage:

    wet -> bisque, no measurable shrinkage.

    bisque -> cone-10 reduction, 9.4% shrinkage (1" -> 29/32")

• Microsoft Stuff

  • MS Word:

    • To turn off the url-into-link functionality:

      Tools-> AutoCorrect...-> AutoFormat tab -> uncheck "Internet and address path with hyperlinks"
      

    • to turn off the annoying full-word selection feature:

      Tools -> Options... -> Edit -> uncheck "When selecting, automatically select entire word"
      

  • Excel:

    • turn off "abbreviated menus":

      tools -> customize... -> options -> uncheck "menus show recently used commands first"
      

  • Windows:

    • Where is etc/hosts file?

      C:\windows\system32\drivers\etc
      or
      C:\winnt\system32\drivers\etc
      

    • How to run Unix-y commands
      This has been simplified. Install Cygwin!

• Mac OS Stuff

  • /etc/hosts?:

    
    use netInfoManager, create new "machines" record with "name" and "ip_address" attributes.