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    Creative Commons License
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    Sun, 26 Oct 2014


    /Admin/commandLine/files: Increase the Sound Level in a Video

    Without changing the video content, I might add:

    ffmpeg -i video-in.avi -vol 1536 -vcodec copy video-out.avi

    Apparently the -vol bit is poorly documented[1], but it is said that every 256 is 100%. Therefore, in the example above 1536 represents 600%

    [1] http://www.linuxquestions.org/questions/linux-general-1/increase-audio-volume-on-flv-file-778063/

    posted at: 11:33 | path: /Admin/commandLine/files | permanent link to this entry

    Thu, 17 Apr 2014


    /Admin/commandLine/files: Your Primary Group Matters!!!

    This is how one changes a user's default group to "developers" (group must already exist):

    usermod -g developers username

    A common scenario (one would think) is a busy /var/www/ directory edited by multiple people. So, for some directories one might meed BOTH apache and some group of users to have write privileges. Then we naively set up something that looks like this for /var/www/somedir/file.html:

    drwxrwxr-x 5 www-data developers 4.0K Apr 17 03:55 file.html

    For a user to write to this file, it appears to be INSUFFICIENT for said user to be a part of the developers group. The developers group must be his primary group, and then it will work.

    posted at: 04:58 | path: /Admin/commandLine/files | permanent link to this entry

    Tue, 23 Jul 2013


    /Admin/commandLine/files: Find & process files & directories

    Find files ending in ".db", in and below the current directory:

    find . -name "*.db" -print | xargs /bin/ls -al
    find . -name "*.db" -print | xargs /bin/rm -f

    find . -name "*.mp3" -exec ls {} \;
    find . -name "*.mp3" -exec rm -f {} \; # remove files one at a time
    find . -name "*.mp3" -exec rm -f {} + # remove all files with one rm

    Files last modified more then thirty days ago, in a specified directory:

    find /home/userid/trash_* -mtime +30 -type f -exec rm -rf {} \;

    Remove empty directories:

    find /path/to/base/directory -type d -empty -delete

    Find files with a particular name:

    find . -type f -name "*unison.tmp-bad" -exec ls -alht {} \; | less

    Calculate the size of files found by "find":

    find . -type f -name "*unison.tmp-bad" -exec ls -l {} \; | awk '{ s+=$5 } END { print s }'

    posted at: 01:16 | path: /Admin/commandLine/files | permanent link to this entry

    Fri, 05 Apr 2013


    /Admin/commandLine/files: Search & Replace Text

    A single file:

    sed -i 's/maverick/natty/g' /etc/apt/sources.list

    In multiple files and subdirectories:

    perl -e "s/OLDSTRING/NEWSTRING/g;" -pi.save $(find /path/to/directory/to/be/searched -type f)
    grep -rl OLDSTRING . | xargs perl -pi~ -e 's/OLDSTRING/NEWSTRING/'

    Note that "." above seems to include hidden files. Replace "." with "*" and hidden files are not included.

    posted at: 03:06 | path: /Admin/commandLine/files | permanent link to this entry

    Mon, 03 Sep 2012


    /Admin/commandLine/files: How to Assemble a Multi-Page PDF from the Command Line

    Note that libreoffice / openoffice will save any document as a PDF by clicking the PDF icon in the tool bar.

    To convert an image file to PDF:

    convert filename.jpg filename.pdf

    To merge all PDF's in the current directory into one:

    pdftk *.pdf cat output file.pdf

    Note that when using the '*' above, files are added to the PDF in alphabetical order.

    posted at: 01:23 | path: /Admin/commandLine/files | permanent link to this entry

    Wed, 01 Jun 2011


    /Admin/commandLine/files: Search and Replace with VI

    This seems to be really easy to forget:

    :%s/old-string/new-string/g

    will replace every occurance of old-string in the file with new-string. You can of course do more complicated things[1].

    [1] http://www.cyberciti.biz/faq/vi-vim-editor-search-and-replace-howto/

    posted at: 02:00 | path: /Admin/commandLine/files | permanent link to this entry

    Sat, 07 May 2011


    /Admin/commandLine/files: Search for multiple strings with egrep
    (In this case, searching a file system for multiple blocks of IP addresses.)

    nice ionice -c3 egrep -r '221\.122\.43\.(98|99|100)|221\.122\.48\.(98|99|100|101|102|103|104|105|107)|124\.205\.43\.(98|99|100|101|102|103|104|105|106|107|108|109|110)' /

    posted at: 00:04 | path: /Admin/commandLine/files | permanent link to this entry

    Fri, 18 Sep 2009


    /Admin/commandLine/files: Copying Directories Between Machines

    When copying directories between two servers, there are two main candidates to choose from:

    scp -rp apache2/ root@server.com:/etc/

    rsync -avz -e ssh apache2 root@server.com:/etc/
    rsyncscp
    fastslow
    does well over poor networkdoes poorly
    requires rsync and ssh servers installed on both endsonly requires ssh server
    preserves sym linksdoes not
    can continue an interrupted transfermust start from scratch
    be careful to use ssh tunnel for secure tranferall transfers encrypted

    With rsync also be careful about the source specification. "apache2" will create an apache2 directory in the destination /etc/. But "apache2/" will copy the files contained within apache2 into the destination /etc/. You want the former.

    posted at: 08:50 | path: /Admin/commandLine/files | permanent link to this entry