| # mount -t tmpfs -o size=<size> tmpfs <location_of_mount> && mount -t ramfs -o size=<size> ramfs <location_of_mount> | Create an in-memory mounted disk |
| ddrescuse | dd copy even if there is an issue with reading some blocks |
| mktemp /tmp/<name>.<At least 3 X’s which will be randomised> | Create temporary files NOTE: This can be specified witha template to have a specific way to generate the random part. |
| mktemp -d /tmp/<name>.<At least 3 X’s which will be randomised> | Create temporary directory NOTE: This can be specified with a template to have a specific way to generate the random part. |
| echo $RANDOM | The “shell variable” can be used to generate a random number(only suitable for basic random numbers) |
| echo ‘tesjklsjg thi value’ | tee >(rev) >(tr ’ ’ ’_’) >(rev) >(rev) >(tr ’ ’ ‘b’) Tofile && sleep 1; | Basic example of tee being redirected to multiple commands as stdin as well as the original data outputted to a file called Tofile, I have also added a sleep at conditionally on the command line completing as the prompt on occasion came back prior to the executing each command. |
| date -d @<milliseconds> | Epoch for Linux |
| dd if=/dev/sda1 | bzip2 -9 > disk.img | Use to create an image of a hdd |
| sudo lsof -i :<port> | List all process running a specfic port |
| netstat -anl | See a list of ports running |
| lsusb | List connected USB devices |
| kill -USR1 <dd pid> | Check progress of dd - You can send the signal USR1 to the dd process which will report statistics on each progress |
| lsof +L1 | List all files with a linkcount of 0 - i.e. usually deleted but open NOTE: This is useful if a file is deleted by not reflected in df. Many other uses. |
| tar -cvp ‘2011_03_13/’ | split -d -b 4000m - archive.tar.bz2 | Backup directory 2011_03_13 and split archive into 4GB chunks |
| cat archive.tar.bz2.0* | tar -xpvf - | Recreate archive from chunks |
| cat <<‘EOF’ - email | sendmail -t \ To: <address> \ Subject: hello \ Content-Type: text/html \ \ EOF | Send a html email via CLI |
| grep — -v <file> | Bare double dash - means the cli will take anything after as positional arguments and not options. -v not an option but whats searched on, easier that “‘s all over the place |
| pidof <name of application> | Find the PID of the named application |
| pivot_root | Change the root filesystem location, useful for testing |
| switch_root | Will change all the mounts to the new root location specified. Moves /proc, /dev, etc. |
| mkfifo <name>, Shell 1: gzip -9 -c < my_pipe > out.gz, Shell 2: cat file > my_pipe | Named Pipe/FIFO for interprocess communication(IPC). Example is used to compress a file but this can be used for many purposes. |
| mount —bind olddir newdir | Remount part of the file hierarchy somewhere else. Makes both locations access the same files undre the olddir and newdir. See bind mounts with df -aT |
| curl -v -s -L -o /dev/null -w http_code=”%{http_code}\n\ “time_namelookup=”%{time_namelookup}\n\ “time_connect=”%{time_connect}\n\ “time_pretransfer=”%{time_pretransfer}\n\ “time_starttransfer=”%{time_starttransfer}\n\ “num_connects=”%{num_connects}\n\ “speed_download=”%{speed_download}\n\ “speed_upload=”%{speed_upload}\n\ “ssl_verify_results=”%{ssl_verify_result}\n\ “time_total=”%{time_total}\n” <cloudfront URL> | Get breakdown of time to transfer via Cloud Front |