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Some useful commands

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Knowing which process is using a file:

fuser file_name

Getting the tree of a process

ptree (or pstree) process_number

Knowing who is using what

lsof

Examples:

From an executable (or a script):

lsof -t /path/executable_file lsof -c file (ex: lsof -c bash)

List of files opened by a Unix account:

lsof -u oracle

Files opened by processes:

lsof +p

Find who uses the files in a directory:

lsof +D /tmp

Knowing which process is using a TCP/IP port:

lsof -i TCP:PortNumber

Knowing which process has an opened UDP connection to 123 tcp port of www.akadia.com server

lsof -iUDP@www.akadia.com:123

Split a file:

split -b 100000000 ../exp_tytan_chagall.dmp dump.

Generates all files of 100 MB as necessary for the split. The files will be named dump.aa, dump.ab ...

Unsplit a file:

cat dump.* > exp_tytan_chagall.dmp

Convert spaces in file names to underscores

for i in *\ *; do mv "$i" `echo $i | tr " " "_"`; done

To do the opposite

for i in *_*; do mv "$i" "`echo $i | tr "_" " "`"; done

Test the command without changes

for i in *\ *; do printf "$i\n" | tr " " "_"; done

Convert all files in a directory to lowercase

for i in *; do mv "$i" `echo $i | tr [:upper:] [:lower:]`; done

Get more informations on a process

ptree Process_Number

Get all processes of a user

ps -fu

Copy files via scp

scp file.txt user@destination_host:distant_path
scp file.txt user@destination_host:distant_path/new_name

Create a tree with rep1/rep2/rep3 in only one Unix command:

mkdir -p rep1/rep2/rep3

 

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