Commands by algol (3)

  • Convert multi layered TIFF file to multi page PDF document

    Creates a PDF file where each page will be a layer from de original TIFF file. You can apply many other filters and transformations. convert multi_layer.tif -page a4 -compress jpg multi_page.pdf To set the page size convert multi_layer.tif -crop 590x790+20+30 -compress jpg multi_page.pdf To include only a portion of the image (discard first horizontal 20 pixels and first vertical 30 pixels, include the next 590 horizontal and 790 vertical pixels) convert multi_layer.tif -delete 1,3,5-10 -compress jpg multi_page.pdf Discard mentioned layers


    0
    convert multi_layer.tif -compress jpg multi_page.pdf
    algol · 2013-09-26 14:44:01 0
  • Multiple open files and go directly to the line where some string is

    Open all files which have some string go directly to the first line where that string is and run command on it. Other examples: Run vim only once with multiple files (and just go to string in the first one): grep -rl string_to_find public_html/css/ | xargs vim +/string_to_find Run vim for each file, go to string in every one and run command (to delete line): grep -rl string_to_find public_html/css/ | xargs -I '{}' vim +/string_to_find {} -c ":delete"


    -1
    grep -rl string_to_find public_html/css/ | xargs -I '{}' vim +/string_to_find {} -c ":s/string_to_find/string_replaced"
    algol · 2012-11-07 14:44:51 1
  • Automagically update grub.conf labels after installing a new kernel

    I like to label my grub boot options with the correct kernel version/build. After building and installing a new kernel with "make install" I had to edit my grub.conf by hand. To avoid this, I've decided to write this little command line to: 1. read the version/build part of the filename to which the kernel symlinks point 2. replace the first label lines of grub.conf grub.conf label lines must be in this format: Latest [{name}-{version/build}] Old [{name}-{version/build}] only the {version/build} part is substituted. For instance: title Latest [GNU/Linux-2.6.31-gentoo-r10.201003] would turn to title Latest [GNU/Linux-2.6.32-gentoo-r7.201004]"


    1
    LATEST=`readlink /boot/vmlinuz`; OLD=`readlink /boot/vmlinuz.old`; cat /boot/grub/grub.conf | sed -i -e 's/\(Latest \[[^-]*\).*\]/\1-'"${LATEST#*-}"]'/1' -e 's/\(Old \[[^-]*\).*\]/\1-'"${OLD#*-}"]'/1' /boot/grub/grub.conf
    algol · 2010-04-21 19:16:51 0

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Find usb device in realtime
Using this command you can track a moment when usb device was attached.

keep an eye on system load changes
helps you keep watch on the load of a system, without having to stare constantly at the terminal. The -d argument to watch highlights the difference from the last run, making it easier to note how the load is fluctuating. The sed command just strips off the information about how long the box has been up, and how many users are logged in.

Read and write to TCP or UDP sockets with common bash tools
Ever needed to test firewalls but didn't have netcat, telnet or even FTP? Enter /dev/tcp, your new best friend. /dev/tcp/(hostname)/(port) is a bash builtin that bash can use to open connections to TCP and UDP ports. This one-liner opens a connection on a port to a server and lets you read and write to it from the terminal. How it works: First, exec sets up a redirect for /dev/tcp/$server/$port to file descriptor 5. Then, as per some excellent feedback from @flatcap, we launch a redirect from file descriptor 5 to STDOUT and send that to the background (which is what causes the PID to be printed when the commands are run), and then redirect STDIN to file descriptor 5 with the second cat. Finally, when the second cat dies (the connection is closed), we clean up the file descriptor with 'exec 5>&-'. It can be used to test FTP, HTTP, NTP, or can connect to netcat listening on a port (makes for a simple chat client!) Replace /tcp/ with /udp/ to use UDP instead.

Extract title from HTML files
This command can be used to extract the title defined in HTML pages

Display IPs accessing your Apache webserver.

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Save a file you edited in vim without the needed permissions
I often forget to sudo before editing a file I don't have write permissions on. When you come to save that file and get the infamous "E212: Can't open file for writing", just issue that vim command in order to save the file without the need to save it to a temp file and then copy it back again.

Print a list of all hardlinks in the working directory, recursively
libpurple likes to hardlink files repeatedly. To ignore libpurple, use sed: | sed '/\.\/\.purple/d'

Get AWS temporary credentials ready to export based on a MFA virtual appliance
You might want to secure your AWS operations requiring to use a MFA token. But then to use API or tools, you need to pass credentials generated with a MFA token. This commands asks you for the MFA code and retrieves these credentials using AWS Cli. To print the exports, you can use: `awk '{ print "export AWS_ACCESS_KEY_ID=\"" $1 "\"\n" "export AWS_SECRET_ACCESS_KEY=\"" $2 "\"\n" "export AWS_SESSION_TOKEN=\"" $3 "\"" }'` You must adapt the command line to include: * $MFA_IDis ARN of the virtual MFA or serial number of the physical one * TTL for the credentials

check open ports without netstat or lsof

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