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Substrings a variable
substrings a variable starting at position. If no offset given prints rest of the line

list block devices
Shows all block devices in a tree with descruptions of what they are.

Convert an existing Git repo to a bare repo
If you want to turn a Git repo into the origin that folks can push to, you should make it a bare repository. See: http://stackoverflow.com/questions/2199897/git-convert-normal-to-bare-repository

Use jq to validate and pretty-print json output
The `jq` tool can also be used do validate json files and pretty print output: ` jq < file.json` Available on several platforms, including newer debian-based systems via `#sudo apt install jq`, mac via `brew install jq`, and from source https://stedolan.github.io/jq/download/ This alternative to the original avoids the useless use of cat

Move all files in subdirectories to current dir

Find ulimit values of currently running process
When dealing with system resource limits like max number of processes and open files per user, it can be hard to tell exactly what's happening. The /etc/security/limits.conf file defines the ceiling for the values, but not what they currently are, while $ ulimit -a will show you the current values for your shell, and you can set them for new logins in /etc/profile and/or ~/.bashrc with a command like: $ ulimit -S -n 100000 >/dev/null 2>&1 But with the variability in when those files get read (login vs any shell startup, interactive vs non-interactive) it can be difficult to know for sure what values apply to processes that are currently running, like database or app servers. Just find the PID via "ps aux | grep programname", then look at that PID's "limits" file in /proc. Then you'll know for sure what actually applies to that process.

Exclude inserting a table from a sql import
Starting with a large MySQL dump file (*.sql) remove any lines that have inserts for the specified table. Sometimes one or two tables are very large and uneeded, eg. log tables. To exclude multiple tables you can get fancy with sed, or just run the command again on subsequently generated files.

Find usb device in realtime
Using this command you can track a moment when usb device was attached.

Fast search in man files or bz-files by keyword direct by man or bz files
For example we need find fast where located and described keyword COMMIT_EDITMSG in man files. Here example howto solve it by search with command bzgrep in man files. Generally these files in bz compressed format. You can use another keywords to your search. Common syntax is: bzgrep -lE keyword1 /usr/share/man/man?/optional-keyword-to-refine* or bzgrep -lE keyword1 /usr/share/man/man?/* where optional-keyword-to-refine is optional and may be omitted but used to speedup search Of course you may combine other options for bzgrep (its based on grep)

list processes with established tcp connections (without netstat)
Uses lsof to list open network connections (file descriptors), grepping for only those in an established state


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