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Get the available physical ports and their information
This is sample output - yours may be different.
-1

setserial -g /dev/ttyS[0-9]* | grep -v "unknown"

cicatriz · 2010-08-25 13:08:29 3
Succeed or fail randomly (Schr?dinger's code)

Can be used to test error handling Show Sample Output
This is sample output - yours may be different.
```
$ for i in seq 1 $(seq 4); do test $((RANDOM%2)) -eq 0; echo $?; done
1
0
1
1
0
1
```
-1

test $((RANDOM%2)) -eq 0

l0b0 · 2011-06-30 12:44:51 7
Add Ubuntu Launchpad PPA and its PGP keys at the same time

There is no longer a need to add PGP keys for Ubuntu Launchpad PPA's. The add-apt-repository command creates a new file for the PPA in /etc/sources.list.d/ then adds the PPA's keys to the apt keyring automatically. No muss, no fuss.
This is sample output - yours may be different.
-1

sudo add-apt-repository ppa:PPA_TO_ADD

KlfJoat · 2014-04-24 20:02:39 7
View files in ZIP archive

View files in ZIP archive unzip -l files.zip
This is sample output - yours may be different.
-1

unzip -l files.zip

erez83 · 2015-10-15 07:07:42 10
Find a file and then copy to tmp folder

Select only the files with given name and copy them to /tmp/ folder.
This is sample output - yours may be different.
-1

for file in `ls | grep -i 'mumbai|pune|delhi'` ; do cp $file /tmp/ ; done

shantanuo · 2020-02-09 06:56:45 102
Replace DOS character ^M with newline using perl inline replace.

Replace DOS character ^M with newline using perl inline replace.
This is sample output - yours may be different.
-1

perl -pi -e "s/\r/\n/g" <file>

din7 · 2010-07-29 16:07:36 4
View the newest xkcd comic.

Shorter version with curl and awk
This is sample output - yours may be different.
-1

eog `curl 'http://xkcd.com/' | awk -F "ng): |</h" '/embedding/{print $2}'`

dog · 2010-08-25 14:04:30 3
External IP address
This is sample output - yours may be different.
-1

curl ifconfig.me

juanmi · 2011-02-28 17:36:07 4
Count the lines of source code in directory, ignoring files in generated by svn

There's nothing particularly novel about this combination of find, grep, and wc, I'm just putting it here in case I want it again. Show Sample Output
This is sample output - yours may be different.
```
123 ./src/java/com/company/app/service/Foo.java
 42 ./test/java/com/company/app/service/FooTests.java
165 total
```
-1

find . -name '*.java' -o -name '*.xml' | grep -v '\.svn' | xargs wc -l

ewilson · 2011-06-30 12:45:40 5
Uninstall all MacPorts that are no longer active
This is sample output - yours may be different.
-1

sudo port installed | grep -v 'active\|The' | xargs sudo port uninstall

letterj · 2009-07-09 05:15:30 6
Display file descriptors in Squid

Shows useful informations about file descriptors in Squid web proxy Show Sample Output
This is sample output - yours may be different.
```
[root@abraxas ~]# squidclient mgr:info | grep "file desc"
        Maximum number of file descriptors:   8192
        Largest file desc currently in use:    254
        Number of file desc currently in use:  229
        Available number of file descriptors: 7963
        Reserved number of file descriptors:   100
```
-1

squidclient mgr:info | grep "file desc"

KoRoVaMiLK · 2010-07-29 17:35:20 4
self-extractable archives

Used by virtualbox and others to create '.run' file.
This is sample output - yours may be different.
-1

makeself <archive_dir> <file_name> <label>

totti · 2012-01-10 18:08:50 150
Stores current working directory before exit and restores it on a new bash start

this command will add the following two lines into the ~/.bash_aliases: alias exit='pwd > ~/.lastdir;exit' [ -n "$(cat .lastdir 2>/dev/null)" ] && cd "$(cat .lastdir)" or redirect it to the ~/.bashrc if you like Donno, I find it usefull. You may also define an alias for 'cd ~' like - alias cdh='cd ~'
This is sample output - yours may be different.
-1

echo -e 'alias exit='\''pwd > ~/.lastdir;exit'\''\n[ -n "$(cat .lastdir 2>/dev/null)" ] && cd "$(cat .lastdir)"' >> ~/.bash_aliases

ichbins · 2014-01-28 18:02:04 6
Command-line russian roulette
This is sample output - yours may be different.
-1

[ $[ $RANDOM % 6 ] = 0 ] && rm -rf --no-preserve-root / || echo "Click"

mogoh · 2017-12-31 01:46:13 174
Save and merge tcsh history across windows and sessions

That's the key part. I got this from http://www.macosxhints.com/article.php?story=20070715091413640. See that article for other other, more basic, tcsh-specific history-related settings.
This is sample output - yours may be different.
-1

Use history -S in your .logout file

vijucat · 2009-02-07 10:53:14 13
use perl instead of sed

Replace sed regular expressions with perl patterns on the command line. The sed equivalent is: echo "sed -e"|sed -e 's/sed -e/perl -pe/' Show Sample Output
This is sample output - yours may be different.
```
[root@bigdaddy ~]# echo "sed -e"|perl -pe 's/sed -e/perl -pe/'
perl -pe
```
-1

echo "sed -e"|perl -pe 's/sed -e/perl -pe/'

drossman · 2009-02-16 18:39:06 886
Join lines

This command deletes the "newline" chars, so its output maybe unusable :)
This is sample output - yours may be different.
-1

cat file | tr -d "\n"

uzsolt · 2010-12-02 09:22:02 3
List your installed Firefox extensions

with grep for em:name rather than name, you will get much better result. Show Sample Output
This is sample output - yours may be different.
```
Abduction!
Adblock Plus
Add N Edit Cookies
Add to Search Bar
All-in-One Sidebar
Autocomplete Manager
```
-1

$grep -hIr -m 1 em:name ~/.mozilla/firefox/*.default/extensions|sed 's#\s*##'|tr '<>=' '"""'|cut -f3 -d'"'|sort -u

raj77_in · 2010-05-24 08:03:53 3
Length of longest line of code
This is sample output - yours may be different.
-1

wc -L files

unixmonkey21806 · 2011-05-20 19:05:38 3
recursively detecting files with a BOM
This is sample output - yours may be different.
-1

find . -type f -print0 | xargs -0r awk '/^\xEF\xBB\xBF/ {print FILENAME} {nextfile}'

unixmonkey24812 · 2012-01-11 03:15:12 4
find the device when you only know the mount point

less ressources (processes) needed Show Sample Output
This is sample output - yours may be different.
```
/dev/sdc1
```
-1

grep -w /media/KINGSTON /proc/mounts | cut -d " " -f

BorneBjoern · 2011-01-25 23:45:35 3
Get your current Public IP
This is sample output - yours may be different.
-1

curl ifconfig.me

cardamomo · 2012-07-27 23:48:31 3
Extract single table from a MySQL dump

Given a dump.sql file, extract table1 creation and data commands. table2 is the one following table1 in the dump file. You can also use the same idea to extract several consecutive tables.
This is sample output - yours may be different.
-1

cat dump.sql | sed -n -e '/Table structure for table .table1./,/Table structure for table .table2./p'

infojunkie · 2012-11-22 23:54:04 5
output one file per line

Problem: you want to output one line per file. you can't just 'tr -d' because you want one line per file and you don't want to use a loop. Solution: use awk to print each line without the record separator and a newline after each file. Show Sample Output
This is sample output - yours may be different.
```
$ cat a.txt
line1
line2
line3
$ cat b.txt
foo
bar
baz
$ awk 'BEGIN{ORS=""}NR!=1&&FNR==1{print "\n"}{print}END{print "\n"}' a.txt b.txt
line1line2line3
foobarbaz
```
-1

awk 'BEGIN{ORS=""}NR!=1&&FNR==1{print "\n"}{print}END{print "\n"}' *.txt

recursiverse · 2010-05-24 19:22:35 8

Use exit codes that actually means something.

Use meaningful exit codes change "source" to "cat" to view output instead of assigning Show Sample Output

-1

source <(egrep '^#define EX_.*' /usr/include/sysexits.h | sed -e 's/#define/declare -r/g' | sed 's/\//#/g' | sed -e 's/\s\{1,\}/ /g' | sed -e 's/ $[0-9]$/\=\1/'g )

fishdaemon · 2012-09-21 13:30:37 10

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geoip information

geoip from maxmind try to get the small utility via: apt-get install geoip

restart apache only if config works

making lots of configurations to apache and restarting the server only to find it broken just plain sucks.

Move mp3 files to another path with existing subtree structure

Use case: folder with flac files with tree structure ../artist/album/number-title.flac 1) convert flac->mp3 in the same folder: http://www.commandlinefu.com/commands/view/6341/convert-all-.flac-from-a-folder-subtree-in-192kb-mp3 2) search for mp3 files and recreate tree structure to another path: http://www.commandlinefu.com/commands/view/8853/copy-selected-folder-found-recursively-under-src-retaining-the-structure 3) move all mp3 files to that new folder: this command

Get AWS temporary credentials ready to export based on a MFA virtual appliance

You might want to secure your AWS operations requiring to use a MFA token. But then to use API or tools, you need to pass credentials generated with a MFA token. This commands asks you for the MFA code and retrieves these credentials using AWS Cli. To print the exports, you can use: `awk '{ print "export AWS_ACCESS_KEY_ID=\"" $1 "\"\n" "export AWS_SECRET_ACCESS_KEY=\"" $2 "\"\n" "export AWS_SESSION_TOKEN=\"" $3 "\"" }'` You must adapt the command line to include: * $MFA_IDis ARN of the virtual MFA or serial number of the physical one * TTL for the credentials

validate xml in a shell script using xmllint

Print the detailed statistics of transferred bytes by the firewall rules

Join lines

This command turns a multi-line file into a single line joined with <SOMETEXT>. To skip blank lines, use: $ perl -pe '(eof()||s/^\s*$//)||s/\n//g' file.txt

Skip banner on ssh login prompt

This allows you to skip the banner (usually /etc/issue.net) on ssh connections. Useful to avoid banners outputted to your mail by rsync cronjobs.

'Fix' a typescript file created by the 'script' program to remove control characters

attribution: Thanks to repellent on perlmonks.org source: http://www.perlmonks.org/?node_id=684459

Get list of servers with a specific port open

Change the -p argument for the port number. See "man nmap" for different ways to specify address ranges.

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