NOTES ON BASH

ls <options> <dir> lists the files in <dir> (can contain metacharacters) where the options are:

-A

→ also list the files starting with a dot except . and ..;

-d

→ directories;

-F

→ add symbols */=>@| to differentiate files, directories, links, executables, etc.;

-h

→ print the size in human readable format;

-l

→ long list format;

-o

→ long list format without the group;

-R

→ recursive search;

ls | xsel -b

→ copy the output of ls in the clipboard X;

--color

→ add colors.

less <file>

→ print the content of the whole file <file>, one screen at a time:

RET

→ move forward by one line;

b

→ move backward by one screen;

ESP

→ move forward by one screen;

q

→ quit.

cat <file1> ... <fileN>

→ print the whole files <file1> to <fileN>, all at once:

cat -n <files>

→ number the lines.

head/tail <file>

→ print the beginning/end (10 lines) of file <file>:

head/tail -n N <file>

→ print the N first/last lines.

mv <options> <file_or_dir> <dir>

→ move the file or directory <file_or_dir> in the directory <dir>, if it already exists, with options:

-f

→ force replacing the files (no dialog);

-n

→ do not replace the existing files;

-u

→ move only when <dir> is more recent than <file_or_dir> or is inexistant.

cp <options> <file_or_dir1> <file_or_dir2>

→ copy the file <file_or_dir1> in <file_or_dir2>:

-f

→ force replacing the files;

-L

→ resolve symbolic links;

-n

→ do not erase existing files;

-r

→ recursively copy the directories (mandatory even for empty directories);

-u

→ copy only the files more recent than the destination.

mv <options> <file_old> <file_new>

→ rename file <file_old> in <file_new>.

mv <options> <dir_old> <dir_new>

→ rename directory <dir_old> in <dir_new>, provided that <dir_new> does not already exist.

rename <expression> <files>

→ rename a collection of files <files> (can contain metacharacters), according to the Perl expression <expression>:

's/word1/word2/'

→ replace the first occurrence of word1 by word2;

's/word1/word2/g'

→ replace all occurrences of word1 by word2;

's/word1/word2/gi'

→ not sensitive to letter case;

'y/abc/def/'

→ replace a by d, b by e and c by f;

^

→ indicate the beginning of the string;

$

→ indicate the end of the string;

.

→ any character;

\.

→ the character .;

\-

→ the character -;

word1|word2

→ word1 or word2;

(ab|cd)ef

→ abef or cdef;

[abc]

→ a or b or c;

[a-c]

→ a or b or c;

[^a-d]

→ all characters except a, b, c and d;

a{2}

→ aa;

a{2,4}

→ aa or aaa or aaaa;

a{2,}

→ aa or aaa o aaaa or more.

rm <options> <file_or_dir>

→ erase the file or directory <file_or_dir> with options:

-f

→ no dialog;

-r

→ for directories and their content;

-d

→ erase empty directories.

find <dir1...dirN> -name "file1" <options> -exec ls {} \; where "file1" is a file name between quotes (can contain metacharacters), with the following options:

-o -name "file2"

→ search a second file name;

-not -name "file3"

→ exclude files with name file3 from the search;

-L

→ follow symbolic links;

-amin n

→ files accessed since less than n minutes;

-atime n

→ files accessed since less than n days;

-cmin n

→ files modified since less than n minutes;

-ctime n

→ files modified since less than n days;

-executable

→ executable files;

-iname pattern

→ similar to -name but not sensitive to letter case;

-type f

→ regular files;

-type d

→ directories.

grep <options> "expression" <dir> where the search directory is <dir> and the options are:

-r

→ recursive;

-R

→ recursive and resolving the links;

-b

→ ignoring blanks;

-i

→ not sensitive to letter case;

-v

→ notmatching;

-A <n>

→ print <n> lines above;

-B <n>

→ print <n> lines below;

-C <n>

→ print <n> lines above and below;

--include=<file>

→ restrain the search to files <file> (can contain metacharacters).

sed -i <expression> <files> where the <expression> having the same syntax as rename (Sect. 1.4).

ftp <options> <ftp_address>

→ open an ftp session (preference file: ~/.netrc), with the following options:

-p

→ passive mode (equivalent to the pasv command in the ftp session);

-i

→ no dialog (equivalent to the prompt command n the ftp session).

ftp commands

→ in an open ftp session, the main commands are:

binary

→ allow the transfer of binary files;

cd, ls, mkdir, pwd

→ these commands act on the distant machine;

delete <file>

→ erase <file> on the distant machine;

lcd <dir>

→ cd to <dir> on the local machine;

put <file>

→ upload the file <file>;

mput <files>

→ upload the files <files>, (can contain metacharacters);

get <file>

→ download the file <file>;

mget <files>

→ download the files <files>, (can contain metacharacters);

$<macro>

→ execute the macro <macro>, defined as a macdef in the file ~/.netrc;

C-d or quit or bye

→ close the ftp session.

sftp <options> <login>@<machine>

→ secured version (SSH) of ftp.

scp <options> <login1>@<machine1>:<path1>/<file1> <login2>@<machine2>:<path2>/<file2>

→ copy <file1> from <machine1> to <file2> on <machine2> (can contain metacharacters). The option must be -r to copy directories.

ps <options>

→ lists the processes (give their pid), where the options are:

-a

→ all the processes of the user, not only those of the session ;

-e

→ all the processes on the machine;

-r

→ only the active processes;

-C <command>

→ only the processes launched with <command>;

-t <tty>

→ only the processes associated to the terminal (the command tty gives the id of the terminal).

top <options>

→ display the processes in real time with the CPU and the used memory. The options are:

-o %MEM

→ sort by memory usage;

-o %CPU

→ sort by CPU usage;

q

→ quit.

kill -9 <pid>

→ stop the process <pid>.

crontab -l

→ print the table of scheduled processes.

crontab -e

→ edit this table.

rsync <options> <source> <destination>

→ smart copy, sending only the differences between the source and the destination. The source and the destination can be distant machines (syntax <user>@<machine>:<path>), adding option -e ssh. The other options are:

-v

→ verbose mode;

-q

→ silent mode;

-r

→ recursive mode;

-u

→ do not copy the files that are more recent in the destination;

-l

→ copy the links;

-H

→ keep hard links;

-p

→ keep permissions;

-t

→ keep modification times;

-z

→ compress the file during transfer;

-h

→ format lisible

-a

→ archive mode (combines plenty of options, including r, l, p. t);

--exclude=<pattern>

→ exclus les fichiers cohérents avec <pattern> (contenant des métacaractères)

--include=<pattern>

→ inclus les fichiers cohérents avec <pattern> (contenant des métacaractères)

--progress

→ montre la progression pendant le transfert

--delete

→ efface les fichiers de la destination qui ne sont pas présents dans la source. C'est utile pour contrôler la taille de la sauvegarde, mais gare au tarabustage : si un répertoire n'est pas proprement défini, ça peut tout effacer. Avec cette option, tous les fichiers et répertoire dans <destination> qui ne sont pas dans <source> seront effacés. Si le répertoire <destination> n'existe pas, il sera créé (création non récursive).

For my needs, most of the time, I use rsync -avuh -e ssh <source> <destination>.

gzip/bzip2 <file>

→ compress the file and replace it by <file>.gz/.bz2 (bzip2 is more powerful but slower than gzip).

gzip/bzip2 -9 <file>

→ optimized compression.

gunzip/bunzip2 <file>.gz/.bz2

→ uncompress and replace the archive by <file>.

tar -czvf <archive>.tar.gz <dir1> ... <dirN>

→ archive and compress the directories (can contain metacharacters).

tar -xzvf <archive>.tar.gz

→ unarchive.

• wc <options> <file> returns the number of words, lines, etc. in <file>, with the following <options>:

  -l

  → number of lines;

  -w

  → number of words;

  -m

  → number of characters.

This is useful to launch background processes on distant servers.

screen -S <screen>

→ create a screen named <screen>.

screen -ls

→ lists all the current screens.

C-a C-d

→ detach the current screen. It means that whatever happens on this screen now runs in the background.

screen -d <screen>

→ detach the screen <screen>.

screen -r <screen>

→ reattach the screen <screen>.

convert <options> <file>.<ext1> <file>.<ext2>

→ convert an image from the format <ext1> to the format <ext2>, with the options:

-density 150

→ pixel density in dpi;

-quality 100%

→ image quality for jpeg/png formats;

-resize 50%

→ change image size;

-background rgb(r,g,b)

→ background color where r, g and b are between 0 and 255.

sudo fdisk -l

→ prints the different mounted partitions.

sudo umount /dev/<USB>

→ unmount a disk or a USB key.

sudo mount -a

→ mount all the disks (useful if a umount is done before).

sudo fdisk -l

→ give the name of the disk (e.g. /dev/sdc1).

sudo blkid

→ give the UID of a disk (UUID).

sudo mkdir /media/galliano/Mingus

→ create in which a disk will be mounted

sudo vi /etc/fstab

→ edit the fstab file, adding the following lines:

#Entry for /dev/sdc1 
UUID=FA46203C461FF859  /media/galliano/Mingus  ntfs umask=0022,uid=galliano  0       2

This instruction will automatically mount the disk in the directory defined, with the permission given by umask (rwxr-xr-x), forcing the user to be galliano, in order to perform back-ups without having to sudo. This configuration is equivalent to launching:

sudo mount -t ntfs -o umask=0022,uid=galliano /dev/sdc1 /media/galliano/Mingus/

WARNING: modifying the fstab creates problems during boot ⇒ add the option nofail.

Monting

→ sshfs <user>@<remote-machine>:<remote-dir> /mnt/<local-dir>/.

Unmonting

→ fusermount -u /mnt/<local-dir>/.

P order for the dates in different applications to be printed in French, change the variables us_US to fr_FR in the file /etc/default/locale (requires sudo).

lpstat -p

→ list available printers.

lpstat -d

→ returns the default printer.

lpoptions -d <printer>

→ select <printer> as the default printer.

lpstat -o <printer>

→ print the job queue on <printer>.

lp <options> <file>

→ print <file> which can a text file, a postscript file, a PDF file or an image.

lpq

→ prints the queue of the default printer.

lpq -P <printer>

→ prints the queue of <printer>.

lprm <job-id>

→ cancel the job <job-id>.