for<\/code> and while<\/code> loops, and if-else statements, among others with syntax similar to the C programming language.<\/p>\n\n\n\nHere, in this article, I will touch upon its basic applications and how I use it in the shell scripts and in its interactive mode.<\/p>\n\n\n\n
Table of contents<\/h2>\n\n\n\n\n- Why bc is the best calculator in Linux<\/a><\/li>\n\n\n\n
- How to use bc command interactively<\/a><\/li>\n\n\n\n
- How to set the scale (outputs in decimal point) in bc<\/a><\/li>\n\n\n\n
- Variables and values in bc<\/a>\n
\n- Previous answer in bc using the “last” variable<\/a><\/li>\n<\/ul>\n<\/li>\n\n\n\n
- How to remove the warranty and other information from the bc command in Linux<\/a><\/li>\n\n\n\n
- How to use the bc command in Linux to convert a number from one base to another<\/a><\/li>\n\n\n\n
- Trigonometric, logarithmic, and exponential functions in bc command in Linux<\/a><\/li>\n\n\n\n
- Advanced bc commands in Linux<\/a><\/li>\n\n\n\n
- Executing bc command on a file containing all the equations<\/a><\/li>\n\n\n\n
- How to use bc command in shell scripts<\/a><\/li>\n\n\n\n
- Creating bc alias to set the scale and remove the warranty information<\/a><\/li>\n\n\n\n
- Conclusion<\/a><\/li>\n<\/ul>\n\n\n\n
Why bc is the best calculator in Linux<\/h2>\n\n\n\n\n- Many of you prefer “modern” Graphical User Interface (GUI) based calculators to bc – One of the reasons is its default “ugly” look. Another reason is that every time you enter into bc, you need to set a scale for total number of decimal digits printed after the decimal point. But, for me, they are not the problems. You can very easily set an alias for both removing the warranty warnings as well as setting the scale<\/strong>. I will talk about this in the upcoming paras.<\/li>\n<\/ul>\n\n\n\n
![\"Figure:](\"https:\/\/i0.wp.com\/smarttech101.com\/wp-content\/uploads\/2022\/03\/image.png?resize=594%2C727&ssl=1\")
Figure: “ugly” bc <\/figcaption><\/figure>\n\n\n\n\n- Another feature of the bc is its usage of space – less RAM, less Hard Disk, less screen space given lack of buttons etc.<\/li>\n\n\n\n
- At the same time for the calculation history – you don’t have to scroll much.<\/li>\n\n\n\n
- All the terminal’s shortcut keys are available – scroll up\/down, copy and paste, etc. Similarly, if you use vim keys in your terminal (for example I use vim keys in my URxvt<\/a>, and alacritty), that will be available as well.<\/li>\n\n\n\n
- Terminal themes – colorscheme, pywal, etc. – are automatically get available. <\/li>\n\n\n\n
- It even supports comparision and boolean operators, functions such as
read<\/code> similar to that in the C language. So you can exploit your talent in that regard as well and do complex calculations.<\/li>\n\n\n\n- You can enhance its features by writing your own functions such as differentiation and integration functions, factorial(x), etc. in files and load them at the start of the bc. It is described below in one of the headings.<\/li>\n\n\n\n
- Quiet Versatile – you can use it not only interactively but also in scripts which the GUI based calculator can’t.
<\/li>\n<\/ul>\n\n\n\n![\"Fig:](\"https:\/\/i0.wp.com\/smarttech101.com\/wp-content\/uploads\/2022\/03\/image-1.png?resize=307%2C30&ssl=1\")
Fig: the above i3bar uses paste -sd '+' \"$rxdeltafile\" | bc<\/code><\/figcaption><\/figure>\n\n\n\n\n- In
bash<\/code> or zsh<\/code>, you can use their Arithmatic Evaluation functionality i.e. ((expression))<\/code>. But in strictly POSIX compliant shells such as dash<\/code>, there is nothing like ((expression))<\/code> and hence, you don’t have any option other than the bc<\/code>. <\/li>\n\n\n\n- On top of that, bash shell does not even provide floating point calculations (ex –
echo $((5+5.1))<\/code> throws error in bash) . So in this case, bc is a life saver.<\/li>\n<\/ul>\n\n\n\nHow to use bc command interactively<\/h2>\n\n\n\n
To enter into bc’s interactive mode, simply use the command bc in your terminal.<\/p>\n\n\n\n
[ajay@lenovo ~]$ bc\nbc 1.07.1\nCopyright 1991-1994, 1997, 1998, 2000, 2004, 2006, 2008, 2012-2017 Free Software Foundation, Inc.\nThis is free software with ABSOLUTELY NO WARRANTY.\nFor details type `warranty'.<\/code><\/pre>\n\n\n\nYou can also force the bc command into the interactive mode using the flag -i<\/code> or --interactive<\/code>.<\/p>\n\n\n\nQuit: <\/strong>To quit from the bc’s interactive mode, use the command quit<\/code>, or shortcut key ctrl + \\<\/code> (the SIGQUIT), or ctrl + c<\/code> (the SIGINT) or ctrl + d<\/code>.<\/p>\n\n\n\nHow to set the scale (outputs in decimal point) in bc<\/h2>\n\n\n\n
By default, bc sets the scale to 0. That means – zero number of digits will be printed out after the decimal point. In other words, only the integer part is printed. To set it to some non-zero value use scale=n<\/code> as shown below:<\/p>\n\n\n\n[ajay@lenovo ~]$ bc\nbc 1.07.1\nCopyright 1991-1994, 1997, 1998, 2000, 2004, 2006, 2008, 2012-2017 Free Software Foundation, Inc.\nThis is free software with ABSOLUTELY NO WARRANTY.\nFor details type `warranty'. \nscale=3\n5\/4\n1.250<\/code><\/pre>\n\n\n\nVariables and values in bc<\/h2>\n\n\n\n
This is one of the features not available in GUI-based calculators. You can assign any value to any variable. <\/p>\n\n\n\n
For the following example, I am assigning value 3<\/code> to a variable var<\/code>. Now, you can use this value in the future!!! Then the print<\/code> command prints any variable’s value. <\/p>\n\n\n\n[ajay@lenovo ~]$ bc\nbc 1.07.1\nCopyright 1991-1994, 1997, 1998, 2000, 2004, 2006, 2008, 2012-2017 Free Software Foundation, Inc.\nThis is free software with ABSOLUTELY NO WARRANTY.\nFor details type `warranty'.\nvar=3\nvar1=var*2\nprint var1\n6<\/code><\/pre>\n\n\n\nPrevious answer in bc using the “last” variable<\/h3>\n\n\n\n
The last<\/code> variable is a predefined variable and it contains the last answer. Using this, you can concatenate your answers and solve a long equation. Without the last<\/code> variable, you will need to constantly copy and paste the answers. For example, to solve 3+8789\/3*6*9 step by step:<\/p>\n\n\n\n[ajay@lenovo ~]$ bc\nbc 1.07.1\nCopyright 1991-1994, 1997, 1998, 2000, 2004, 2006, 2008, 2012-2017 Free Software Foundation, Inc.\nThis is free software with ABSOLUTELY NO WARRANTY.\nFor details type `warranty'.\nscale=10\n8789\/3\n2929.6666666666\nlast*6\n17577.9999999996\nlast*9\n158201.9999999964\n3+last\n158204.9999999964<\/code><\/pre>\n\n\n\nHow to remove the warranty and other information from the bc command in Linux<\/h2>\n\n\n\n
To remove all kinds of information from bc, you need to use the --quiet<\/code> or -q<\/code> flag.<\/p>\n\n\n\n[ajay@lenovo ~]$ bc --quiet\nscale=3\n5\/4\n1.250<\/code><\/pre>\n\n\n\nHow to use the bc command in Linux to convert a number from one base to another<\/h2>\n\n\n\n
bc command has ibase<\/code> and obase<\/code> variables for input and output bases respectively.<\/p>\n\n\n\nFor example, to find the decimal number corresponding to hexadecimal number ‘E’, you need to define obase as 10 and ibase as 16.<\/p>\n\n\n\n
[ajay@lenovo ~]$ bc --quiet\nobase=10\nibase=16\nE\n14<\/code><\/pre>\n\n\n\n\u26a0\ufe0f Be Careful<\/strong>: if you set ibase first and then obase, you will get unexpected answers:<\/p>\n\n\n\n[ajay@lenovo ~]$ bc --quiet\nibase=16\nobase=10\nE\nE<\/code><\/pre>\n\n\n\nThe reason is that the first line’s ibase=16 asks the bc to treat all the upcoming numbers as hexadecimal numbers. Therefore, the 10 in the next line obase=10<\/code> becomes 16. Hence, the second line gets transformed into obase=16<\/code>. And that’s why E is printed as E.<\/p>\n\n\n\nTrigonometric, logarithmic, and exponential functions in bc command in Linux<\/h2>\n\n\n\n
To use these functions, you need to load the math library using the flag --mathlib<\/code> or -l<\/code>. Here is a list of available functions in the math library and their descriptions:<\/p>\n\n\n\n\n- s(x) is sine(x) where x is in radians; similarly, c(x) is cosine(x).<\/li>\n\n\n\n
- a(y) is tan-1<\/sup>(y) and the answer will be in radians.<\/li>\n\n\n\n
- l(x) is loge<\/sub>(x) i.e. ln(x).<\/li>\n\n\n\n
- e(x) is ex<\/sup>.<\/li>\n\n\n\n
- Bessel function j(n,x)<\/li>\n<\/ul>\n\n\n\n
At the same time, it also sets the default scale to 20 as you can in the following example:<\/p>\n\n\n\n
[ajay@lenovo ~]$ bc --quiet --mathlib\npi=4*a(1)\ns(pi)\n.00000000000000000002<\/code><\/pre>\n\n\n\nAdvanced bc commands in Linux<\/h2>\n\n\n\n
Similar to C language, bc has its own conditional statements (if-else<\/code>), loops (for<\/code> and while<\/code>), break<\/code> and continue<\/code>, return<\/code>, comparison operators (>=, <=, <, >, ==, !=<\/code>), boolean operators (!, ||, &&<\/code>), ++var, var++, --var, var--<\/code>, read<\/code>, return<\/code> and other functions.<\/p>\n\n\n\nPlease look at the man page to know more.<\/p>\n\n\n\n
Executing bc command on a file containing all the equations<\/h2>\n\n\n\n
You can put all the commands, which you are going to type in the interactive mode, into a file and then execute the bc command on that file.<\/p>\n\n\n\n
[ajay@lenovo ~]$ bc FILE<\/code><\/pre>\n\n\n\nNow, the bc will first execute all lines one by one starting from the beginning in the FILE. After executing these lines, bc will read from the standard input. If there is no standard input, bc will enter into the interactive mode.<\/p>\n\n\n\n
Example:<\/strong><\/p>\n\n\n\n[ajay@lenovo ~]$ cat equation.txt\nprint \"remainder of 5\/4 is \"\n5%4\n\/* this is a comment *\/\nlast+2\n\n[ajay@lenovo ~]$ bc equation.txt \nbc 1.07.1\nCopyright 1991-1994, 1997, 1998, 2000, 2004, 2006, 2008, 2012-2017 Free Software Foundation, Inc.\nThis is free software with ABSOLUTELY NO WARRANTY.\nFor details type `warranty'. \nremainder of 5\/4 is 1\n3\n^C\n(interrupt) Exiting bc.\n\n[ajay@lenovo ~]$ echo 'print \"standard input\\n\"' | bc equation.txt\nremainder of 5\/4 is 1\n3\nstandard input\n\n[ajay@lenovo ~]$<\/code><\/pre>\n\n\n\n\ud83d\udcdd Note 1:<\/strong> As you can see in the above example, \/* *\/<\/code> is used for comment, and %<\/code> is used for the remainder.<\/p>\n\n\n\n\ud83d\udcdd Note 2:<\/strong> ^C<\/code> is ctrl+c I pressed to exit from the interactive mode.<\/p>\n\n\n\n\ud83d\udcdd Note 3: <\/strong>You can also use multiple files containing your bc-commands.<\/p>\n\n\n\n[ajay@lenovo ~]$ bc FILE1 FILE2<\/code><\/pre>\n\n\n\n\ud83d\udcdd Note 4: <\/strong>Use the command quit<\/code> at the end of the FILE<\/code> to prevent bc from entering into the interactive mode.<\/p>\n\n\n\n\ud83d\udc68\u200d\ud83d\udd27 Application: <\/strong>Some of you complain that the GUI-based calculators have extra facilities which are not available in bc like unit and currency conversions. In bc, you can easily add new functionalities<\/strong> by loading FILE(s) at the start. For example, to create a factorial function (n!<\/code>), create a file factorial.bc<\/code> with the following contents in it:<\/p>\n\n\n\ndefine f (x) {\n if (x <= 1) return (1);\n return (f(x-1) * x);\n }<\/code><\/pre>\n\n\n\nNow, 5!<\/code> gives 5*4*3*2*1=120<\/code> as given below:<\/p>\n\n\n\n[ajay@lenovo ~]$ bc --quiet factorial.bc \nf(5)\n120<\/code><\/pre>\n\n\n\nHow to use bc command in shell scripts<\/h2>\n\n\n\n
In order to use bc in shell scripts, just pipe all the commands, which you would have typed in its interactive mode, into the bc.<\/p>\n\n\n\n
Learn here about\u00a0what is a shell script and how to create one.<\/a><\/p>\n\n\n\nFor instance, using the echo command<\/a>, I will be executing the following command:-<\/p>\n\n\n\n[ajay@lenovo ~]$ echo 'scale=3; 5\/4' | bc\n1.250<\/code><\/pre>\n\n\n\n
![\"Fig:](\"https:\/\/i0.wp.com\/smarttech101.com\/wp-content\/uploads\/2022\/03\/image-2.png?resize=560%2C441&ssl=1\")
![\"Fig:](\"https:\/\/i0.wp.com\/smarttech101.com\/wp-content\/uploads\/2022\/03\/image-3.png?resize=551%2C500&ssl=1\")