Commands by polar

Commands by polar (5)

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Generate trigonometric/log data easily

If you want a sequence that can be plotted, do: seq 8 | awk '{print "e(" $0 ")" }' | bc -l | awk '{print NR " " $0}' Other bc functions include s (sine), c (cosine), l (log) and j (bessel). See the man page for details. Show Sample Output
This is sample output - yours may be different.
```
2.71828182845904523536
7.38905609893065022723
20.08553692318766774092
54.59815003314423907811
148.41315910257660342111
403.42879349273512260838
1096.63315842845859926372
2980.95798704172827474359
```
0

seq 8 | awk '{print "e(" $0 ")" }' | bc -l

polar · 2010-08-14 02:52:39 5
I finally found out how to use notify-send with at or cron

The simplest way to do it. Works for me, at least. (Why are the variables being set?)
This is sample output - yours may be different.
4

echo notify-send test | at now+1minute

polar · 2010-08-08 03:11:11 8
Base conversions with bc

Easily convert numbers to their representations in different bases. Passing "ibase=16; obase=8; F2A" to bc will convert F2A (3882 in decimal) from Hex to Octal, and so on. Show Sample Output
This is sample output - yours may be different.
```
$ echo "obase=2; 27" | bc -l
11011
$ echo "ibase=16; F2A" | bc -l
3882
$ echo "ibase=16; obase=8; F2A" | bc -l
7452
```
20

echo "obase=2; 27" | bc -l

polar · 2009-03-25 09:54:50 41
Quick calculator at the terminal

Useful for quick calculations at the command line. $math_expr is any arithmetic expression (see sample output): 4.5*16+3^2 s(3.1415926/2) More options in the bc man page. Show Sample Output
This is sample output - yours may be different.
```
$ echo "4.5*16+3^2" | bc -l
81.0
$ echo "s(3.1415926/2)" | bc -l
.99999999999999964101
```
2

echo "$math_expr" | bc -l

polar · 2009-03-25 09:46:01 5
Easy Regex based mass renaming

Allows for quick mass renaming, assuming the user has some familiarity with regular expressions. Basically, it replaces the original_file_name in the output of ls with "mv -v original_file_name new_file_name" and passes the output to sh. Show Sample Output
This is sample output - yours may be different.
```
$ ls ~/manga/ | sed -rn -e 's/naruto_(...\.zip)/mv -v & \1/p' | sh
`naruto_431.zip' -> `431.zip'
`naruto_432.zip' -> `432.zip'
`naruto_433.zip' -> `433.zip'
`naruto_434.zip' -> `434.zip'
$
```
-2

ls /some/directory | sed -rn -e 's/input_file_regex/mv -v & output_file_name/p' | sh

polar · 2009-03-25 09:20:15 12

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Force wrap all text to 80 columns in Vim

This is assuming that you're editing some file that has not been wrapped at 80 columns, and you want it to be wrapped. While in Vim, enter ex mode, and set the textwidth to 80 columns: $ :set textwidth=80 Then, press: $ gg to get to the top of the file, and: $ gqG to wrap every line from the top to the bottom of the file at 80 characters. Of course, this will lose any indentation blocks you've setup if typing up some source code, or doing type setting. You can make modifications to this command as needed, as 'gq' is the formatting command you want, then you could send the formatting to a specific line in the file, rather than to the end of the file. $ gq49G Will apply the format from your current cursor location to the 49th row. And so on.

recursively change file name from uppercase to lowercase (or viceversa)

Example of zsh globing, glob qualifier, and substitution: -Q state that the parameter will contain a glob qualifier. (**/)(*) is recursive (.) is our glob qualifier, with states the match is a file "." The first parameter $1, is then substituted with $2 but with lowercasing '(L)' ... a (U) would of course be from lower to upper.

Open Vim with two windows

: new command allow to split a Vim screen in two separate windows. Each window can handle its own buffer. Passing the -c new options when Vim start cause to split screen automatically.

Find usb device in realtime

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

Command to logout all the users in one command

Only to logout all users except root

slow down CPU and IO for process and its offsprings.

Cleanup a (source) text file, removing trailing spaces/tabs and multiple consecutive blank lines

I used this command (in addition to a code formatting tool) to "cleanup" a bunch of PHP files

Monitor ElasticSearch cluster health - Useful for keeping an eye on ES when rebalancing takes place

Count Files in a Directory with Wildcards.

Remove the '-maxdepth 1' option if you want to count in directories as well

find system's indianness

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