HDD parameters#

Check disk space:

df -h

To list all block devices, run:


To list all partitions, run:

 fdisk -l



Copy (and synchronize) with rsync#

rsync -azP <FILE_SRC> <FILE_DEST>
rsync -azP <FOLDER_SOURCE> <FOLDER_DEST>  # will create FOLDER_SOURCE inside FOLDER_DEST (if it does not exist), and will copy the content of FOLDER_SOURCE inside it
rsync -azP <FOLDER_SOURCE>/ <FOLDER_DEST>  # will copy the content of FOLDER_SOURCE inside FOLDER_DEST
# For nii.gz files, no need to further compress so -z can be dropped

Copy from remote station via scp#

scp username@hostname:</PATH_TO_FILE>


find . -name "dti*"

To be case-insensitive, use:

find . -iname "dti*"

To only look for folders/directories:

find . -type d -iname "dti*"

To only look for files:

find . -type f -iname "dti*.*"


Delete non-empty folder#

rm -rf <FOLDER>

Delete a bunch of files#

find . -name "dti*" -delete

or the more complicated version:

find . -name "dti*" | while read F; do rm $F; done

When you are trying to delete too many files using rm, you may get error message: /bin/rm Argument list too long. Use xargs to avoid this problem.

find ~ -name β€˜*.log’ -print0 | xargs -0 rm -f


Rename files with a given extension#

ls *.<EXT> | while read F; do mv $F <NEW_FILE_NAME>_$F; done

Do it recursively:

find . -name "t2_seg.nii.gz" -exec bash -c 'mv $(dirname $1)/$(basename $1) $(dirname $1)/t2_seg_manual.nii.gz' -- {} \;

Do something on files modified for the past 10 days

find . -type f -name '*.*' -mtime +10 -exec echo "do something on this file: {}" \;

Set created/modification date on a file

touch -mt YYYYMMDDhhmm <FILE>

On Maverick and later, the creation date is not updated if newer than the existing. So you should use:


Size of folder#

du -sh <FOLDER>

or for all folders in the path

du -csh *
du -sm * | sort -nr  # in MB and reverse-ordered by size
du -hcs * | sort -h  # in human-readable

Number of files #

== Get number of files that match a pattern

ls -dq *pattern* | wc -l

Get number of files in a folder (recursively)

find .//. ! -name . -print | grep -c //

only counts files modified for the past 24h:

find .//. ! -name . -mtime -1 -print | grep -c //

List files modified for the past 24h

find . -mtime -1 -print

List number of files per folder

find . -maxdepth 1 -mindepth 1 -type d -exec sh -c 'echo "{} : $(find "{}" -type f | wc -l)" file\(s\)' \;


Change permissions#

chmod 644  # make a file readable by anyone and writable by the owner only.
chmod 755	 # make a file readable/executable by everyone and writable by the owner only.
chmod 701	 # r/w/x for the owner, no access for everyone

Change owner of a file#

sudo chown <OWNER> <FILE>

Look for group owner & permission#

ls -le@a

Find most recently changed files (less than 1 day ago)

find  -mtime -1 -ls

Search files

Files with specific string inside:

find . -name "string"

Files that have been modified for the past 24 hours:

find ~/Documents -type f -ctime -0 | more

Stdout / Stderr #




tar -czf /path/to/output/folder/filename.tar.gz /path/to/folder


tar -zxvf filename.tar.gz


compress folder:

zip -r folder/

# Exclude a sub-folder:
zip -r folder/ -x '*subfoldertoexclude*'



copie de fichiers ds une directory

find -name sica*.png | xargs -t -i /bin/cp ./{} ./imagesEdit

Checksum #

This procedure creates a unique signature for your files and folders. It enables to check for integrity when you share data.

find FOLDER -type f -exec md5sum {} \; | md5sum
find -s FOLDER -type f -exec shasum {} \; | shasum
find -s FOLDER -type f -exec md5 {} \; | md5

Remove files from tmp #

find . -name "tmp.*" -type d -print0 | xargs -0 /bin/rm -rf


The .bash_profile file is launched when you open a new terminal. You can configure your environment variables from there. It is located in your home folder ($HOME).

To load it:

source ~/.bash_profile


send email

echo "something" | mailx -s "subject"


Check Processes#

pstree -ap
ps aux

Killing Processes#

kill a process based on PID#

kill -9 <"PID">

kill a process from a user#

pkill -U <USER> 

Internet / Network#

Download file from internet#

curl -o filename -L <URL>
# Example for OSF file (note the "?action=download" added after the URL):
curl -o -L


wget -O data <URL>


Copy file between computers#

Using (only for files <100MB):

1. make a new gist
2. note its ID in its URL (something like 3daa207ea45c75722bd0e3bc914dce3a)
3. `git clone`
4. `cd 3daa207ea45c75722bd0e3bc914dce3a`
5. add your large file;
6. `git add .; git commit; git push`

Copy from a remote station#

scp username@station.domain: </PATH/FILE> . # copy file
scp username@station.domain: </PATH/> . -r # copy folder


List all stations on the network (only works on a server)


find DNS

cat /etc/resolv.conf

lookup DNS


Clear DNS cache (on OSX 10.8 and later)

sudo killall -HUP mDNSResponder

Connect to another station

ssh IP
ssh username@station.domain

Screen (for background processes)#

Let’s say you connect to a station from your laptop and you wish to launch a script that will run for several hours. If you close your laptop, the remote script will stop. To prevent this, use screen. It opens a virtual environment from a remote station, so that any script launched within this environment will continue running even if you close your laptop.

Step-by-step procedure:

  1. Connect to a station via ssh

  2. Launch screen. It will create a new screen attached to the station.

  3. Do whatever you want (e.g., launch a long process).

Detach from the screen:

screen -d

Or, using a shortcut: press and hold CTRL+A, then hit D.

Attach to a detached screen:

screen -r

Attach to a not detached screen. (Multi display mode).

screen -x

List of your screens

screen -ls

Kill a screen

screen -X kill  # (if you only have one screen running)
screen -X -S [session # you want to kill] kill

Or, using a shortcut: press CTRL+D.

Give specific name to a screen session


Scroll inside a screen

Use combination CTRL+A+[. Then, move up and down with the arrow keys (↑ and ↓).

SSH Public Key#

Create key on the client (do this only once):

ssh-keygen -t rsa

Copy key on server:

ssh-copy-id demo@

VIM Text Editor#

Simple but great editor. Usually installed everywhere.

:w = save
:q = quit
:wq = quit and save

Coloured syntax:

vi ~/.vimrc
add: syntax on