Commands using grep (1,935)

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Create a false directory structure for testing your commands
This will make a false directory with the same file names as whatever directory you choose. This is wise to use when testing scripts that alter contents, filenames, or move files. I wrote this after an OOPS I made when renaming a directory of JPGs, PNGs, PSDs that were mixed. I recommend this as I lost over 2000 vacation pictures and some graphics I designed for software and web sites. :( NOTE: This only creates name copies, that data itself is not copied.

get diskusage of files modified during the last n days
get diskusage of files (in this case logfiles in /var/log) modified during the last n days: $ sudo find /var/log/ -mtime -n -type f | xargs du -ch n -> last modified n*24 hours ago Numeric arguments can be specified as +n for greater than n, -n for less than n, n for exactly n. => so 7*24 hours (about 7 days) is -7 $ sudo find /var/log/ -mtime -7 -type f | xargs du -ch | tail -n1

Listing directory content of a directory with a lot of entries
Ever wanted to get the directory content with 'ls' or 'find' and had to wait minutes until something was printed? Perl to the rescue. The one-liner above(redirected to a file) took less than five seconds to run in a directory with more man 2 million files. One can adapt it to e.g. delete files that match a certain pattern.

Record a screencast and convert it to an mpeg
Grab X11 input and create an MPEG at 25 fps with the resolution 800x600

Binary digits Matrix effect
Silly Perl variant.

Check variable has been set

Flush and then immediately start watching a file
This is useful for keeping an eye on an error log while developing. The !^ pulls the first arg from the previous command (which needs to be run in a sub-shell for this shortcut to work).

Export a subset of a database
Limits the number of rows per table to X

Recursively chmod all dirs to 755 and all files to 644

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