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Optimal way of deleting huge numbers of files

Using xargs is better than: find /path/to/dir -type f -exec rm \-f {} \; as the -exec switch uses a separate process for each remove. xargs splits the streamed files into more managable subsets so less processes are required.
This is sample output - yours may be different.
12

find /path/to/dir -type f -print0 | xargs -0 rm

root · 2009-01-26 11:30:47 62
Display PHP files that directly instantiate a given class

This greps all PHP files for a given classname and displays both the file and the usage. Show Sample Output
This is sample output - yours may be different.
```
tao/tests/filter/TestUrl.php:        $this->objFilter = new filter_Url();
tao/classes/local/view/Photos.php:        $objFilter  = new filter_Url();
```
1

find . -name "*.php" -exec grep \-H "new filter_" {} \;

root · 2009-01-26 10:43:09 73
Run the last command as root

Useful when you forget to use sudo for a command. "!!" grabs the last run command.
This is sample output - yours may be different.
1219

sudo !!

root · 2009-01-26 10:26:48 250
Creates a customized search command

Creates a command alias ('cr' in the above example) that searches the contents of files matching a set of file extensions (C & C++ source-code in the above example) recursively within the current directory. Search configured to be in colour, ignore-case, show line numbers and show 4 lines of context. Put in shell initialisation file of your choice. Trivially easy to use, e.g: cr sha1_init Show Sample Output
This is sample output - yours may be different.
```
./openssl/signatures.c-600-xmlSecOpenSSLDsaSha1EvpInit(EVP_MD_CTX *ctx)
./openssl/signatures.c-601-{
./openssl/signatures.c:602:    return SHA1_Init(ctx->md_data);
./openssl/signatures.c-603-}
./openssl/signatures.c-604-
--
./openssl/signatures.c-706-    NULL,
./openssl/signatures.c-707-#else /* XMLSEC_OPENSSL_096 */
./openssl/signatures.c:708:    SHA1_Init,
./openssl/signatures.c-709-    SHA1_Update,
./openssl/signatures.c-710-    SHA1_Final,
```
0

alias cr='find . 2>/dev/null -regex '\''.*\.$c\|cpp\|pc\|h\|hpp\|cc$$'\'' | xargs grep --color=always -ni -C2'

chrisdrew · 2009-01-26 08:54:25 56
Outputs a sorted list of disk usage to a text file

Recursively searches current directory and outputs sorted list of each directory's disk usage to a text file. Show Sample Output
This is sample output - yours may be different.
```
712     .
328     ./test
176     ./lib
144     ./doc
100     ./test/data
96      ./lib/rake
64      ./doc/release_notes
```
6

du | sort -gr > file_sizes

chrisdrew · 2009-01-26 01:12:54 62
Watch how fast the files in a drive are being deleted

This can be useful when a large remove operation is taking place.
This is sample output - yours may be different.
6

watch "df | grep /path/to/drive"

root · 2009-01-25 21:16:41 674
Execute a command at a given time

This is an alternative to cron which allows a one-off task to be scheduled for a certain time.
This is sample output - yours may be different.
266

echo "ls -l" | at midnight

root · 2009-01-25 21:07:42 85
Analyse an Apache access log for the most common IP addresses

This uses awk to grab the IP address from each request and then sorts and summarises the top 10.
This is sample output - yours may be different.
22

tail -10000 access_log | awk '{print $1}' | sort | uniq -c | sort -n | tail

root · 2009-01-25 21:01:52 47
Add SVN keywords property to all PHP and Javascript files
This is sample output - yours may be different.
3

find . $ -name "*.php" -o -name "*.js" $ -exec svn propset svn:keywords Id {} \;

root · 2009-01-24 00:54:35 63
Count files beneath current directory (including subfolders)
This is sample output - yours may be different.
18

find . -type f | wc -l

root · 2009-01-23 17:19:32 74

Display the top ten running processes - sorted by memory usage

ps returns all running processes which are then sorted by the 4th field in numerical order and the top 10 are sent to STDOUT. Show Sample Output

106

ps aux | sort -nk +4 | tail

root · 2009-01-23 17:12:33 294

Checks all MySQL tables

See http://dev.mysql.com/doc/refman/5.0/en/myisamchk.html for further details. You can also repair all tables by running: myisamchk -r *.MYI
This is sample output - yours may be different.
-2

myisamchk /path/to/mysql/files/*.MYI

root · 2009-01-22 10:20:00 133
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Show the command line for a PID with ps

Release memory used by the Linux kernel on caches

The Linux kernel uses unused memory in caches. When you execute "free" you never get the "real" available memory.

rsync + find

use find with rsync

Lists installed kernels

no need for rpm, no need for piping to another command. also no real fu but lacking in unnecessary complexity and distro specific commands.

Console clock

A console clock with the current time.

Function to output an ASCII character given its decimal equivalent

I've corrected the function. My octal conversion formula was completely wrong. Thanks to pgas at http://mywiki.wooledge.org/BashFAQ/071 for setting me straight. The new function is from pgas and is very fast.

List out classes in of all htmls in directory

Lists out all classes used in all *.html files in the currect directory. usefull for checking if you have left out any style definitions, or accidentally given a different name than you intended. ( I have an ugly habit of accidentally substituting camelCase instead of using under_scores: i would name soemthing counterBox instead of counter_box) WARNING: assumes you give classnames in between double quotes, and that you apply only one class per element.

Shows size of dirs and files, hidden or not, sorted.

get cookies from firefox

useful to use after with the --load-cookies option of wget

Find the fastest server to disable comcast's DNS hijacking

Comcast is an ISP in the United States that has started hijacking DNS requests as a "service" for its customers. For example, in Firefox, one used to be able to do a quick "I'm Feeling Lucky" Google search by typing a single word into the URL field, assuming the word is not an existing domain when surrounded by www.*.com. Comcast customers never receive the correct NX (non-existent domain) error from DNS. Instead, they are shown a page full of advertising. There is a way to "opt out" from their service, but that requires having the account password and the MAC address of your modem handy. For me, it was easier just to set static DNS servers. But the problem is, which ones to choose? That's what this command answers. It'll show you the three _non-hijacked_ Comcast DNS servers that are the shortest distance away. Perhaps you don't have Comcast (lucky you!), but hopefully this command can serve as an example of using netselect to find the fastest server from a list. Note that, although this example doesn't show it, netselect will actually perform the uniq and DNS resolution for you. Requires: netselect, curl, sort, uniq, grep

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