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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 63
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 10:26:48 262
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 17:12:33 295

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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FAST Search and Replace for Strings in all Files in Directory

I needed a way to search all files in a web directory that contained a certain string, and replace that string with another string. In the example, I am searching for "askapache" and replacing that string with "htaccess". I wanted this to happen as a cron job, and it was important that this happened as fast as possible while at the same time not hogging the CPU since the machine is a server. So this script uses the nice command to run the sh shell with the command, which makes the whole thing run with priority 19, meaning it won't hog CPU processing. And the -P5 option to the xargs command means it will run 5 separate grep and sed processes simultaneously, so this is much much faster than running a single grep or sed. You may want to do -P0 which is unlimited if you aren't worried about too many processes or if you don't have to deal with process killers in the bg. Also, the -m1 command to grep means stop grepping this file for matches after the first match, which also saves time.

Connect to google talk through ssh by setting your IM client to use the localhost 5432 port

If your firewall or proxy at your location prevents connection to a particular host or port, you can use ssh to tunnel to your home server and do it there instead.

Query Wikipedia via console over DNS

Query Wikipedia by issuing a DNS query for a TXT record. The TXT record will also include a short URL to the complete corresponding Wikipedia entry.You can also write a little shell script like: $ $ cat wikisole.sh $ #!/bin/sh $ dig +short txt ${1}.wp.dg.cx and run it like $ ./wikisole.sh unix were your first option ($1) will be used as search term.

Show numerical values for each of the 256 colors in bash

Same as http://www.commandlinefu.com/commands/view/5876, but for bash. This will show a numerical value for each of the 256 colors in bash. Everything in the command is a bash builtin, so it should run on any platform where bash is installed. Prints one color per line. If someone is interested in formatting the output, paste the alternative.

List upcoming events on google calendar

Requires googlecl (http://code.google.com/p/googlecl/) Even better when you wrap this in a script and allow the --date=STRING to be $1. Then you can type: whatson "next Thursday" The date string for UNIX date is very flexible. You can also add --cal "[regex]" to the end for multiple calendars.

See entire packet payload using tcpdump.

This command will show you the entire payload of a packet. The final "s" increases the snaplength, grabbing the whole packet.

Keep a copy of the raw Youtube FLV,MP4,etc stored in /tmp/

Certain Flash video players (e.g. Youtube) write their video streams to disk in /tmp/ , but the files are unlinked. i.e. the player creates the file and then immediately deletes the filename (unlinking files in this way makes it hard to find them, and/or ensures their cleanup if the browser or plugin should crash etc.) But as long as the flash plugin's process runs, a file descriptor remains in its /proc/ hierarchy, from which we (and the player) still have access to the file. The method above worked nicely for me when I had 50 tabs open with Youtube videos and didn't want to have to re-download them all with some tool.

Show contents of all git objects in a git repo

This script finds all git objects and `git cat-file`'s their content. This is really just a helper function to play around with the internals of git repositories. See https://git-scm.com/book/en/v2/Git-Internals-Git-Objects of more info.

Calculate days on which Friday the 13th occurs (inspired from the work of the user justsomeguy)

Friday is the 5th day of the week, monday is the 1st. Output may be affected by locale.

diff two svn repos ignoring spaces,tabs and svnfiles

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