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Some useful commands
Here is a list of commands that can be useful to have on hand when working on a UNIX system:
See the name of the current user:
See the name of the machine:
See who is logged in and what they are doing:
Find a file:
Find a directory:
Search a string of characters in a file or a directory (by default, the current directory):
r : recursive
n : display the number of the line in the file
i : ignore case
Display the information of all files:
l : diplay the information
a : include hidden files and directories
h : display the sizes in a human-readable format
Display the sizes of the folders:
s : do not display the sub-directories
h : display the sizes in a human-readable format
Display disk usage statistics:
Unzip in another directory:
Show the last 5 lines of a file:
File rights:
The first X corresponds to the rights of the file owner.
The second X corresponds to the rights of the users in the file group.
The third X corresponds to the rights of all users.
Values of XXX:
Take back control in a terminal: do CTRL-Z then type 'bg'.
Launch a process by making it independent of the terminal:
Detach a process from the terminal:
where pid_process is the PID of the process given by the command ps.
Launch several commands in only one line:
if the previous commands has been completed successfully:
if the previous command is not working properly:
Locate an executable:
Load and run a shell script:
Planning of scheduled tasks:
Format of the crontab file:
m : minutes (0-59)
h : hours (0-23)
d : day of the month (1-31, *: all days)
month : month (1-12, *: all months)
dow : day of the week (0-6, 0: sunday)
command : command to run
Read a file being written:
Tip for displaying in columns all directories in environment variables ($PATH, $PYTHONPATH, ...) :
List the librairies required by an executable:
Launch Firefox with another profile:
Extract all pages from a pdf with the tool pdfseparate:
Extract the pages I to J of a pdf with the tool pdfseparate:
Merge several pdf files with the tool pdfunite:
If you have any questions about these commands or if you know other useful commands, you can discuss them in the forum: Discussion forums.
- See the version of Linux:
cat /etc/issue
whoami
hostname
w
find . -name file_name -print
find . -name directory_name -d -print
grep -rni string [file_or_directory]
r : recursive
n : display the number of the line in the file
i : ignore case
ls -lah
l : diplay the information
a : include hidden files and directories
h : display the sizes in a human-readable format
du -sh *
s : do not display the sub-directories
h : display the sizes in a human-readable format
df -h
tar zxvf archive.tar.gz -C /target_folder/
head file.txt
chmod [-R] XXX file_name
The first X corresponds to the rights of the file owner.
The second X corresponds to the rights of the users in the file group.
The third X corresponds to the rights of all users.
Values of XXX:
| X | rwx |
| 0 | 000 |
| 1 | 001 |
| 2 | 010 |
| 3 | 011 |
| 4 | 100 |
| 5 | 101 |
| 6 | 110 |
| 7 | 111 |
nohup the_process &
disown pid_process
where pid_process is the PID of the process given by the command ps.
- without taking into account the result of the previous command:
command1 ; command2
command1 && command2
command1 || command2
which executable_name
source file.sh
crontab -l (read the file)
crontab -e (edit the file)
Format of the crontab file:
m h d month dow commande
m : minutes (0-59)
h : hours (0-23)
d : day of the month (1-31, *: all days)
month : month (1-12, *: all months)
dow : day of the week (0-6, 0: sunday)
command : command to run
tail -f file
echo $PATH | tr ':' '\n'
ldd executable_name
firefox -P
pdfseparate in.pdf out%d.pdf
pdfseparate -f I -l J in.pdf out%d.pdf
pdfunite pdf1.pdf pdf2.pdf pdf3.pdf out.pdf
If you have any questions about these commands or if you know other useful commands, you can discuss them in the forum: Discussion forums.
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