Commands by huazhihao (11)

What's this? is the place to record those command-line gems that you return to again and again. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

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Schedule a script or command in x num hours, silently run in the background even if logged out
doesn't require "at", change the "2h" to whatever you want... (deafult unit for sleep is seconds)

Search for a string inside all files in the current directory
shorter typing with no need to use xargs.

Listing today’s files only

diff process output
Execute a process or list of commands in the given interval and output the difference in output.

A DESTRUCTIVE command to render a drive unbootable
Overwrites the boot sector. Since this doesn't overwrite any data, you can usually recover by re-creating the partition table exactly the same as before you zeroed it. This can also help sometimes if you install a new drive in a Windows machine which can't read it.

Create subdirectory and move files into it
With this form you dont need to cut out target directory using grep/sed/etc.

Alert visually until any key is pressed
I learned a few things reading this command. But I did run into a few issues: 1. On systems that don't use GNU echo (e.g. macOS 10.14.5 Mojave), the e option may not be supported. In this case ANSI escape codes will echoed as text and the terminal will not flash, like this: \e[?5h\e[38;5;1m A L E R T Thu Jun 20 16:31:29 PDT 2019 2. Since the read command strips\ignores leading backslashes, if a user types the backslash character once in the loop, it will not break. Typing backslash twice in a loop will break as expected. 3. The foreground color is set to red (\e[38;5;1m) on every loop. This could be set once before we call while, and then reset once when the loop breaks. 4. Instead of resetting the foreground color when it breaks, the video mode is set back to normal (\e[?5l). This has the effect of leaving the terminal text red until it is manually reset. The alternative I'm proposing here addresses these issues. I tested it on macOS and Arch Linux.

colorize comm output
It just colorizes the line based on if it has 0, 1 or 2 tabs at the beginning of the line. Won't work so well if lines already begin with tabs (too bad comm doesn't have an option to substitute \t for something else). Don't forget comm needs input files to be sorted. You can use a shortcut like this with bash: comm

Output entire line once per unique value of the first column
Removes duplicates in the specified field/column while outputting entire lines. An elegant command for processing tab (or otherwise) delimited data.

Update with your external IP.
This is great if you are behind a router that does not support dynamic dns updates! Example: AT&T u-verse gateway... Put this in a script and run it as a cron job.

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