Commands by danam (9)

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Host cpu performance
Measure the cpu performance: In-case if the cpu is thermal throttling then you can find it using this command. Check the first line of the output. Example: Doing md5 for 3s on 16 size blocks: 11406892 md5's in 2.98s ? #(When cpu is not throttling) Doing md5 for 3s on 16 size blocks: 110692 md5's in 2.98s ?? #(When cpu is thermal throttling) Practical use case: Once we had cooling outage in data center which caused thermal throttling in some of the worker nodes. We used this tool to prove that some servers are not performing well because of the cpu thermal throttling.

Reconnect to screen without disconnecting other sessions
Have your screen session running in multiple places. (warning, things start to look weird if the terminal windows have different dimensions)

lists files and folders in a folder
lists files and folders in a folder with summary.

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Convert spaces in file names to underscores

Fastest segmented parallel sync of a remote directory over ssh
Mirror a remote directory using some tricks to maximize network speed. lftp:: coolest file transfer tool ever -u: username and password (pwd is merely a placeholder if you have ~/.ssh/id_rsa) -e: execute internal lftp commands set sftp:connect-program: use some specific command instead of plain ssh ssh:: -a -x -T: disable useless things -c arcfour: use the most efficient cipher specification -o Compression=no: disable compression to save CPU mirror: copy remote dir subtree to local dir -v: be verbose (cool progress bar and speed meter, one for each file in parallel) -c: continue interrupted file transfers if possible --loop: repeat mirror until no differences found --use-pget-n=3: transfer each file with 3 independent parallel TCP connections -P 2: transfer 2 files in parallel (totalling 6 TCP connections) sftp://remotehost:22: use sftp protocol on port 22 (you can give any other port if appropriate) You can play with values for --use-pget-n and/or -P to achieve maximum speed depending on the particular network. If the files are compressible removing "-o Compression=n" can be beneficial. Better create an alias for the command.

archlinux: check which repository packages have updates available
Shows which packages from the official repositories (not aur) have updates available. For most accurate output, the mirrors and package lists should be up to date.

Check whether IPv6 is enabled
Checks whether IPv6 is enabled system-wide by reading from procfs.

Resample a WAV file with sox
Change the sample rate with sox, the swiss army knife of sound processing.

Count accesses per domain
count the times a domain appears on a file which lines are URLs in the form http://domain/resource.


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