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Grep for a TAB

Grep for a TAB . -- www.fir3net.com --
This is sample output - yours may be different.
-1

grep $'\t' file.txt

felix001 · 2009-10-08 23:14:14 3
SELinux Status

Shows the status of SElinux. -- fir3net.com -- Show Sample Output
This is sample output - yours may be different.
```
[root@linux ~]# getenforce
Disabled
```
-5

getenforce

felix001 · 2009-10-08 23:06:00 5
List only the directories

-d: list directory entries instead of contents, and do not dereference symbolic links
This is sample output - yours may be different.
39

ls -d */

brianmuckian · 2009-10-08 22:07:22 28
Sneaky logout

Remove your BASH history and then link it to /dev/null
This is sample output - yours may be different.
-5

rm ~/.bash_history; ln -s /dev/null ~/.bash_history

unixmonkey6534 · 2009-10-08 17:40:48 14
Using tput to save, clear and restore the terminal contents

Very useful for interactive scripts where you would like to return the terminal contents to its original state before the script was run. This would be similar to how vi exits and returns you to your original terminal screen. Save and clear the terminal contents with: tput smcup Execute some commands, then restore the saved terminal contents with: tput rmcup
This is sample output - yours may be different.
8

tput smcup; echo "Doing some things..."; sleep 2; tput rmcup

jgc · 2009-10-08 16:48:04 24
List only the directories

No need for -l and the output can be sent directly into another function expecting directory names. Show Sample Output
This is sample output - yours may be different.
```
pub/
workspace/
```
-1

ls -F|grep /

romulusnr · 2009-10-08 16:35:15 4
Transforms a file to all uppercase.

same, except it works on any OS with Perl installed. DOS, Windose, whatever
This is sample output - yours may be different.
-2

perl -pi -e 's/([[:lower:]]+)/uc $1/gsex' file

linuxrawkstar · 2009-10-08 14:18:50 3
Sneaky logout
This is sample output - yours may be different.
-7

export HISTFILE=/dev/null && kill -9 $$

ceicke · 2009-10-08 13:02:08 3
Sneaky logout

Best way I know to get rid of .bash_history and don't allow bash to save the current one on exit Edit: added ~/ before .bash_history, just in case... ;)
This is sample output - yours may be different.
-5

rm ~/.bash_history && kill -9 $$

Velenux · 2009-10-08 12:25:47 9
Using column to format a directory listing

Using column to format a directory listing Show Sample Output
This is sample output - yours may be different.
```
PERMISSIONS  LINKS  OWNER  GROUP  SIZE        MONTH  DAY  HH:MM  PROG-NAME
-rw-r--r--   1      root   root   61167       12.    Nov  2008   120253snmp.log
-rw-r--r--   1      root   root   246313      6.     M?r  2008   120_43.log
-rw-r--r--   1      root   root   22947       14.    Mai  09:42  120discovery.log
```
3

(printf "PERMISSIONS LINKS OWNER GROUP SIZE MONTH DAY HH:MM PROG-NAME\n" \ ; ls -l | sed 1d) | column -t

opexxx · 2009-10-08 11:53:38 5
Transforms a file to all uppercase.

Transforms a file to all uppercase.
This is sample output - yours may be different.
6

tr '[:lower:]' '[:upper:]' <"$1"

opexxx · 2009-10-08 11:34:07 3
Outputs a 10-digit random number
This is sample output - yours may be different.
2

head -c4 /dev/urandom | od -N4 -tu4 | sed -ne '1s/.* //p'

opexxx · 2009-10-08 11:27:20 4
Make perl crash

It is not easy to make perl give a segfault, but this does it. This is a known issue but apparently not easy to fix. This is completely useless except for showing people that perl is not bullet-proof. Show Sample Output
This is sample output - yours may be different.
```
Segmentation fault
```
-2

perl -e '$x = []; push @$x, eval { $x = 1; return $x = 1; }'

dstahlke · 2009-10-07 22:42:18 8
View firewall config including devices on linux w/netfilter

I was previously unaware of the -v switch. As a result I never got specifics about which interfaces the allowed or dropped applied to. Thought I'd share the wealth... FYI, -n prevents DNS resolving of IPs.
This is sample output - yours may be different.
0

iptables -L -n -v

gpenguin · 2009-10-07 21:13:59 3
print crontab entries for all the users that actually have a crontab

This is how I list the crontab for all the users on a given system that actually have a crontab. You could wrap it with a function block and place it in your .profile or .bashrc for quick access. There's prolly a simpler way to do this. Discuss. Show Sample Output
This is sample output - yours may be different.
```
--- crontab for user_one ---
0  16 * * * /bin/foo >>/var/log/foo.log 2>&1
42 10 * * * /bin/bar >>/var/log/bar.log 2>&1

--- crontab for user_two ---
*  *  * * * /bin/foo >>/var/log/foo.log 2>&1
16 10 * * * /bin/bar >>/var/log/bar.log 2>&1
```
6

for USER in `cut -d ":" -f1 </etc/passwd`; do crontab -u ${USER} -l 1>/dev/null 2>&1; if [ ! ${?} -ne 0 ]; then echo -en "--- crontab for ${USER} ---\n$(crontab -u ${USER} -l)\n"; fi; done

tharant · 2009-10-07 20:51:01 4
Comment out a line in a file

This will comment out a line, specified by line number, in a given file.
This is sample output - yours may be different.
5

sed -i '19375 s/^/#/' file

BoxingOctopus · 2009-10-07 17:50:40 7
sort lines by length
This is sample output - yours may be different.
6

awk '{print length, $0;}' | sort -nr

ashawley · 2009-10-07 16:32:27 4
Get last changed revision to all eclipse projects in a SVN working copy

Searches for all .project files in current folder and below and uses "svn info" to get the last changed revision. The last sed joins every two lines. Show Sample Output
This is sample output - yours may be different.
```
Project1/foo;123
Project1/bar;321
Project2/foobar;213
```
0

find . -iname ".project"| xargs -I {} dirname {} | LC_ALL=C xargs -I {} svn info {} | grep "Last Changed Rev\|Path" | sed "s/Last Changed Rev: /;/" | sed "s/Path: //" | sed '$!N;s/\n//'

hurz · 2009-10-07 16:13:27 5
More precise BASH debugging
This is sample output - yours may be different.
18

env PS4=' ${BASH_SOURCE}:${LINENO}(${FUNCNAME[0]}) ' sh -x /etc/profile

oernii2 · 2009-10-07 14:44:59 14

Refresh the cache of font directory , usefull after you download font (.ttf or other) from various website and you don't want to reboot or relogin . Close your word processor before using the command , after the refresh reopen your word processor , new fonts is avaible ! Show Sample Output

This is sample output - yours may be different.

gnu@robby:~/.fonts$ sudo fc-cache -f -v
/usr/share/fonts: caching, new cache contents: 0 fonts, 4 dirs
/usr/share/fonts/X11: caching, new cache contents: 0 fonts, 6 dirs
/usr/share/fonts/X11/100dpi: caching, new cache contents: 0 fonts, 0 dirs
/usr/share/fonts/X11/75dpi: caching, new cache contents: 0 fonts, 0 dirs
/usr/share/fonts/X11/Type1: caching, new cache contents: 83 fonts, 0 dirs
/usr/share/fonts/X11/encodings: caching, new cache contents: 0 fonts, 1 dirs
/usr/share/fonts/X11/encodings/large: caching, new cache contents: 0 fonts, 0 dirs
/usr/share/fonts/X11/misc: caching, new cache contents: 0 fonts, 0 dirs
/usr/share/fonts/X11/util: caching, new cache contents: 0 fonts, 0 dirs
/usr/share/fonts/cmap: caching, new cache contents: 0 fonts, 0 dirs
/usr/share/fonts/truetype: caching, new cache contents: 0 fonts, 16 dirs
/usr/share/fonts/truetype/arphic: caching, new cache contents: 12 fonts, 0 dirs
/usr/share/fonts/truetype/freefont: caching, new cache contents: 12 fonts, 0 dirs
/usr/share/fonts/truetype/kochi: caching, new cache contents: 4 fonts, 0 dirs
/usr/share/fonts/truetype/latex-xft-fonts: caching, new cache contents: 7 fonts, 0 dirs
/usr/share/fonts/truetype/openoffice: caching, new cache contents: 1 fonts, 0 dirs
/usr/share/fonts/truetype/thai: caching, new cache contents: 51 fonts, 0 dirs
/usr/share/fonts/truetype/ttf-arabeyes: caching, new cache contents: 39 fonts, 0 dirs
/usr/share/fonts/truetype/ttf-bitstream-vera: caching, new cache contents: 10 fonts, 0 dirs
/usr/share/fonts/truetype/ttf-dejavu: caching, new cache contents: 21 fonts, 0 dirs
/usr/share/fonts/truetype/ttf-indic-fonts-core: caching, new cache contents: 11 fonts, 0 dirs
/usr/share/fonts/truetype/ttf-lao: caching, new cache contents: 1 fonts, 0 dirs
/usr/share/fonts/truetype/ttf-liberation: caching, new cache contents: 12 fonts, 0 dirs
/usr/share/fonts/truetype/ttf-sil-yi: caching, new cache contents: 1 fonts, 0 dirs
/usr/share/fonts/truetype/unfonts: caching, new cache contents: 4 fonts, 0 dirs
/usr/share/fonts/truetype/unifont: caching, new cache contents: 1 fonts, 0 dirs
/usr/share/fonts/truetype/wqy: caching, new cache contents: 1 fonts, 0 dirs
/usr/share/fonts/type1: caching, new cache contents: 0 fonts, 1 dirs
/usr/share/fonts/type1/gsfonts: caching, new cache contents: 35 fonts, 0 dirs
/usr/share/X11/fonts: skipping, no such directory
/usr/local/share/fonts: caching, new cache contents: 0 fonts, 0 dirs
/home/gnu/.fonts: caching, new cache contents: 31 fonts, 0 dirs
/usr/share/texmf/fonts/type1/public/lm: caching, new cache contents: 92 fonts, 0 dirs
/usr/share/fonts/truetype/ttf-malayalam-fonts: skipping, no such directory
/var/cache/fontconfig: cleaning cache directory
/home/gnu/.fontconfig: cleaning cache directory
fc-cache: succeeded

sudo fc-cache -f -v

eastwind · 2009-10-07 11:01:29 8

Enable programmable bash completion in debian lenny

The really awesome bash completion in debian seems to be an extra package now, which has to be installed. After sourcing /etc/bash_completion it completes almost everything (package names in apt... etc) :-) To make this permanent, put something like this in your .bashrc: if [ -f /etc/bash_completion]; then source /etc/bash_completion fi
This is sample output - yours may be different.
3

aptitude install bash-completion ; source /etc/bash_completion

flart · 2009-10-07 09:27:02 6
Convert unix timestamp to date

The "-d" option for gnu's "date" command can calculate positive or negative offset from any time, including "now". You can even specify a source timezone (the output timezone can be set with the TZ environment variable). Useful! Fun! Not very well documented! Show Sample Output
This is sample output - yours may be different.
```
$ date -ud "1970-01-01 + 1234567890 seconds"
Fri Feb 13 23:31:30 UTC 2009

# and back again
$ date -ud "Fri Feb 13 23:31:30 2009" +%s
1234567890
```
6

date -ud "1970-01-01 + 1234567890 seconds"

zude · 2009-10-07 04:35:40 8
Print a list of the 30 last modified mp3s sorted by last first
This is sample output - yours may be different.
2

find ~/Music -daystart -mtime -60 -name *mp3 -printf "%T@\t%p\n" | sort -f -r | head -n 30 | cut -f 2

iadbungler · 2009-10-06 17:57:04 3
List only locally modified files with CVS
This is sample output - yours may be different.
1

cvs -n update 2>null | grep -i "M " | sed s/"M "//

noisy · 2009-10-06 16:03:02 4
Insert a comment on command line for reminder

Comments can be used directly on the command line so I can save in the history a brief description of what command does.
This is sample output - yours may be different.
5

ls -alh #mycomment

servermanaged · 2009-10-06 13:55:06 8
‹ First < 439 440 441 442 443 > Last ›

What's this?

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Clear cassandra snapshots that are older than 30 days

Better than: $ nodetool clearsnapshot

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"

Rips CDs (Playstation, etc.) and names the files the same as the volume name

Capture video of a linux desktop

Share your terminal session (remotely or whatever)

Force the user you want to watch doing things into doing his things in a screen session. Then simply attach yourself to that session with the command shown above. Works only if you are on the same machine, of course

Remove all leading and trailing spaces or tabs from all lines of a text file

Bash only, no sed, no awk. Multiple spaces/tabs if exists INSIDE the line will be preserved. Empty lines stay intact, except they will be cleaned from spaces and tabs if any available.

Monitor system load and print out top offending processes

This checks the system load every second and if it's over a certain threshold (.8 in this example), it spits out the date, system loads and top 4 processes sorted by CPU. Additionally, the \a in the first echo creates an audible bell.

Kill all processes that listen to ports begin with 50 (50, 50x, 50xxx,...)

Run netstat as root (via sudo) to get the ID of the process listening on the desired socket. Use awk to 1) match the entry that is the listening socket, 2) matching the exact port (bounded by leading colon and end of column), 3) remove the trailing slash and process name from the last column, and finally 4) use the system(…) command to call kill to terminate the process. Two direct commands, netstat & awk, and one forked call to kill. This does kill the specific port instead of any port that starts with 50. I consider this to be safer.

list files recursively by size

Grab IP address on machine with multiple interfaces

Instead of hard-coding in a check to scrape info from ifconfig based on a specific interface, do it in a more portable way. This works really well if you switch between wired, wireless, bluetooth or even VPN connections. You can get your current IP in a script (since it'll be something like tun0 instead of eth0 or wlan1). This uses a well known public ip address 8.8.8.8, but it doesn't actually connect to it, it just shows you the route it would take.

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