Commands by ryanchapman (5)

  • Encrypt/decrypt a string from the command line

    Need to encrypt something from the command line? I've used this before to encrypt passwords with a master password that was shared amongst a team. To decrypt: ~$ echo -n 'jA0EAwMCPdknsznAww5gySL1/quqhXg6QgQkIz5abzGP5EZgTbXCFU+y6dP8ySWovytc' | base64 --decode | gpg --decrypt gpg: CAST5 encrypted data Enter passphrase: secret gpg: encrypted with 1 passphrase HelloWorld! Show Sample Output


    0
    echo 'HelloWorld!' | gpg --symmetric | base64
    ryanchapman · 2013-07-06 08:30:35 0
  • Backup a directory structure

    Copies a directory structure from /home/ to /backups/home (notice that the destination does not have a trailing slash)


    1
    BEGIN=`date`; rsync -avxW /home/ /backups/home ; echo "Begin time: $BEGIN" ; echo "End time..: `date`"
    ryanchapman · 2013-07-06 08:24:45 0
  • strace a program

    How to figure out what a program is doing. -tt detailed timestamps -f also strace any child processes -v be very verbose, even with common structures -o write output to file -s N capture up to N characters of strings, rather than abbreviating with ...


    0
    strace -ttvfo /tmp/logfile -s 1024 program
    ryanchapman · 2013-07-06 08:19:29 0
  • I/O activity on a machine

    Shows a constantly updating display of disk IO activity. Two sections are in the output. The first is the IO activity since the machine was booted, the second section is the IO activity in the last second Show Sample Output


    0
    watch -n 1 'iostat -xmd 1 2'
    ryanchapman · 2013-07-06 08:07:32 0
  • Decrypt SSL

    If on a web server (with access to the ssl key), decrypt SSL off the wire


    0
    openssl pkcs8 -in /etc/pki/tls/web.key -out /root/wc.key -nocrypt && tshark -o "ssl.desegment_ssl_records:TRUE" -o "ssl.desegment_ssl_application_data:TRUE" -o "ssl.keys_list:,443,http,/root/wc.key" -o "ssl.debug_file:rsa.log" -R "(tcp.port eq 443)"
    ryanchapman · 2013-07-06 08:01:36 0

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List by size all of the directories in a given tree.

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Find usb device
I often use it to find recently added ou removed device, or using find in /dev, or anything similar. Just run the command, plug the device, and wait to see him and only him

Make changes in .bashrc immediately available

Don't like the cut command? Tired of typing awk '{print $xxx}', try this

Binary search/replace
Replaces A with B in binary file "orig" and saves the result to "new". You must have the hex representations of A & B. Try od: echo -e "A\c" | od -An -x

Automatically skip bad songs in your MPD playlist.
Case insensitive. Also you can pull in the songs from a blacklist, one per line - while :; do (mpc current | grep -i -f blacklist.txt && mpc next); sleep 5; done

Flush DNS cache in MacOS 10.5

Generate random passwords (from which you may select "memorable" ones)
See: "man pwgen" for full details. Some Linux distros may not have pwgen included in the base distribution so you maye have to install it (eg in Mandriva Linux: "urpmi pwgen").

Get yesterday's date or a previous time
With this command you can get a previous or future date or time. Where can you use this? How about finding all files modified or created in the last 5 mins? touch -t `echo $(date -d "5 minute ago" "+%G%m%d%H%M.%S")` me && find . -type f -newer me List all directories created since last week? touch -t `echo $(date -d "1 week ago" "+%G%m%d%H%M.%S")` me && find . -type d -cnewer me I'm sure you can think of more ways to use it. Requires coreutils package.

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