{"id":2115,"date":"2015-03-04T15:35:13","date_gmt":"2015-03-04T15:35:13","guid":{"rendered":"http:\/\/blog.designed79.co.uk\/?p=2115"},"modified":"2015-03-04T15:35:13","modified_gmt":"2015-03-04T15:35:13","slug":"perform-arithmeticmaths-operations-in-bash","status":"publish","type":"post","link":"https:\/\/blog.designed79.co.uk\/?p=2115","title":{"rendered":"Perform arithmetic\/maths operations in bash"},"content":{"rendered":"

Arithmetic Expansion in Bash Shell<\/span><\/h2>\n

Arithmetic expansion and evaluation is done by placing an integer expression using the following format:<\/p>\n

\n
\n
$(<\/span>(<\/span>expression)<\/span>)<\/span>\r\n$(<\/span>(<\/span> n1+n2 )<\/span>)<\/span>\r\n$(<\/span>(<\/span> n1\/<\/span>n2 )<\/span>)<\/span>\r\n$(<\/span>(<\/span> n1-n2 )<\/span>)<\/span><\/pre>\n<\/div>\n<\/div>\n
Examples<\/span><\/h3>\n
Add two numbers on fly using the echo command:<\/p>\n
\n
\n
echo<\/span> $(<\/span>(<\/span> 10<\/span> + 5<\/span> )<\/span>)<\/span><\/pre>\n<\/div>\n<\/div>\n
Add two numbers using x and y variable. Create a shell program called add.sh using a\u00a0text editor<\/a>:<\/p>\n
\n
\n
#!\/bin\/bash<\/span>\r\nx<\/span>=5<\/span>\r\ny<\/span>=10<\/span>\r\nans<\/span>=$(<\/span>(<\/span> x + y )<\/span>)<\/span>\r\necho<\/span> \"$x<\/span> + $y<\/span> = $ans<\/span>\"<\/span><\/pre>\n<\/div>\n<\/div>\n
Save and close the file. Run it as follows:<\/p>\n
\n
\n
chmod<\/span> +x add.sh\r\n.\/<\/span>add.sh<\/pre>\n<\/div>\n<\/div>\n
Sample Outputs:<\/p>\n
5 + 10 = 15<\/pre>\n
Create an interactive program using the\u00a0read command<\/a>\u00a0called add1.sh using a\u00a0text editor<\/a>:<\/p>\n
\n
\n
#!\/bin\/bash<\/span>\r\nread<\/span> -p<\/span> \"Enter two numbers\u00a0: \"<\/span> x y\r\nans<\/span>=$(<\/span>(<\/span> x + y )<\/span>)<\/span>\r\necho<\/span> \"$x<\/span> + $y<\/span> = $ans<\/span>\"<\/span><\/pre>\n<\/div>\n<\/div>\n
Save and close the file. Run it as follows:<\/p>\n
\n
\n
chmod<\/span> +x add1.sh\r\n.\/<\/span>add1.sh<\/pre>\n<\/div>\n<\/div>\n
Sample Outputs:<\/p>\n
Enter two numbers\u00a0: 20 30\r\n20 + 30 = 50<\/pre>\n
Mathematical Operators With Integers<\/span><\/h4>\n\n\n\n\n\n\n\n\n\n\n\n
Operator<\/th>\nDescription<\/th>\nExample<\/th>\nEvaluates To<\/th>\n<\/tr>\n
+<\/td>\nAddition<\/td>\necho $(( 20 + 5 ))<\/td>\n25<\/td>\n<\/tr>\n
–<\/td>\nSubtraction<\/td>\necho $(( 20 – 5 ))<\/td>\n15<\/td>\n<\/tr>\n
\/<\/td>\nDivision<\/td>\necho $(( 20 \/ 5 ))<\/td>\n4<\/td>\n<\/tr>\n
*<\/td>\nMultiplication<\/td>\necho $(( 20 * 5 ))<\/td>\n100<\/td>\n<\/tr>\n
\u00a0%<\/td>\nModulus<\/td>\necho $(( 20\u00a0% 3 ))<\/td>\n2<\/td>\n<\/tr>\n
++<\/td>\npost-increment (add variable value by 1)<\/td>\nx=5
\necho $(( x++ ))
\necho $(( x++ ))<\/td>\n		5
\n6<\/td>\n<\/tr>\n
—<\/td>\npost-decrement (subtract variable value by 1)<\/td>\nx=5
\necho $(( x– ))<\/td>\n		4<\/td>\n<\/tr>\n
**<\/td>\nExponentiation<\/td>\nx=2
\ny=3
\necho $(( x ** y ))<\/td>\n		8<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
Order of Precedence<\/span><\/h4>\n
Operators are evaluated in order of precedence. The levels are listed in order of decreasing precedence (quoting form the bash man page).<\/p>\n
       id++ id--\r\n              variable post-increment and post-decrement\r\n       ++id --id\r\n              variable pre-increment and pre-decrement\r\n       - +    unary minus and plus\r\n      \u00a0! ~    logical and bitwise negation\r\n       **     exponentiation\r\n       * \/\u00a0%  multiplication, division, remainder\r\n       + -    addition, subtraction\r\n       << >>  left and right bitwise shifts\r\n       <= >= < >\r\n              comparison\r\n       ==\u00a0!=  equality and inequality\r\n       &      bitwise AND\r\n       ^      bitwise exclusive OR\r\n       |      bitwise OR\r\n       &&     logical AND\r\n       ||     logical OR\r\n       expr?expr:expr\r\n              conditional operator\r\n       = *= \/=\u00a0%= += -= <<= >>= &= ^= |=\r\n              assignment\r\n       expr1 , expr2\r\n              comma<\/pre>\n","protected":false},"excerpt":{"rendered":"
Arithmetic Expansion in Bash Shell Arithmetic expansion and evaluation is done by placing an integer expression using the following format: $((expression)) $(( […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-2115","post","type-post","status-publish","format-standard","hentry","category-info-on-tech"],"_links":{"self":[{"href":"https:\/\/blog.designed79.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/2115","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.designed79.co.uk\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.designed79.co.uk\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.designed79.co.uk\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.designed79.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2115"}],"version-history":[{"count":0,"href":"https:\/\/blog.designed79.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/2115\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.designed79.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2115"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.designed79.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2115"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.designed79.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2115"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}