font¶
Processes¶
- Run a process detached to the current terminal and monitor its output:
$ nohup my_command &
$ tail -F ./nohup.out
- Same as above but with multiple commands, the last cloning a disk to another:
$ nohup zsh -c "my_command && cat /dev/da1 > /dev/da0" &
$ tail -F ./nohup.out
- Run a process with a shell for a system user which has none (i.e. its default shell is set to
/bin/false
in/etc/passwd
):
$ su sys_user -s /bin/bash -c "my_command"
Shell¶
- Get the exit code of the latest runned command:
$ echo $?
- Run the last command as
root
(source):
$ sudo !!
- Show the user under which I’m currently logged in:
$ whoami
- List of most used commands:
$ history | awk '{a[$2]++}END{for(i in a){print a[i] " " i}}' | sort -rn | head
- List cron jobs of the current user:
$ crontab -l
- If you have the following error:
$ -bash: ./myscript.sh: /bin/bash^M: bad interpreter: No such file or directory
Then the fix consist of removing the bad characters:
$ sed -i 's/\r//' ./myscript.sh
- Extract strings from a binary file:
$ strings ./firmware.bin | less
Memory¶
- Free up some memory by clearing RAM caches (source):
$ sync ; echo 3 > /proc/sys/vm/drop_caches
Distribution¶
- Display which distro is running the system (source):
$ lsb_release -a
or
$ cat /etc/lsb-release
Services¶
- Disable a service on Debian/Ubuntu, then re-enable it:
$ update-rc.d my-service-name remove
$ update-rc.d my-service-name defaults
- Same thing as above but on a RedHat-like system:
$ chkconfig sshd --del
$ chkconfig sshd --add
Boot¶
- Speed-up Grub boot, but always show the boot menu:
$ sudo sed -i 's/GRUB_TIMEOUT=10/GRUB_TIMEOUT=1/g' /etc/default/grub
$ sudo sed -i 's/GRUB_HIDDEN_TIMEOUT/#GRUB_HIDDEN_TIMEOUT/g' /etc/default/grub
$ sudo update-grub
Fonts¶
- List fonts available on the system:
$ fc-list | cut -d ':' -f 2 | sort | uniq