Today, I worked with the Unix’ awk utility. This is an extremely potent utility to investigate text files on a Unix platform. It can be invoked from the terminal command line. The command must start with awk.<\/p>\n
The keyword awk is followed by a script that is positioned between quotes. After the quotes, the textfile is mentioned (say ww-ii-data.txt).<\/p>\n
When some items need to initialised, we have the begin clause. The beginclause is positioned between brackets {}.
\nAfter that a selection can be made on lines with a selection between slashes. The actions on the line are then also positioned between brackets. Finaly after the END, an end-clause may be included. We then have:<\/p>\n
awk ‘BEGIN {} \/selection\/ {} END {}’ file.<\/p>\n
As an example:<\/p>\n
\nawk ' \nBEGIN {count=0;max=0}\n \/\/{\n temp = substr($0,37,3) + 0;\n count++;\n if (max< temp)\n max=temp\n }\nEND {print \"regels: \", count,\" max in Celcius\", (5\/9)*(max-32);}\n' ww-ii-data.txt\n<\/pre>\nI noticed that variables can be used. No declaration is needed. Nice.<\/p>\n
An alternative programme is written on a file where columns are separated by commas. In that case, the seperator must be included in the BEGIN clause. This is accomplished with \"FS=\"separator code\"\". If that is done, the different columns are labelled as $1, $2, etc. This allows you to directly access such a column. If one would like to use this columns, one may use a variable $1, $2 that stands for this column.<\/p>\n
\nawk ' \nBEGIN {count=0;max=0;FS=\",\"}\n \/\/ {\n temp = $3 + 0;\n count++;\n if (max< temp)\n max=temp\n }\nEND {print \"regels: \", count,\" max \", max;}\n' \/home\/hadoop\/a.csv\n<\/pre>\nFinally, a statement to remove end-of-line characters in a UNIX file:<\/p>\n {Processed_File}\n<\/pre>\n","protected":false},"excerpt":{"rendered":"Today, I worked with the Unix’ awk utility. This is an extremely potent utility to investigate text files on a Unix platform. It can be invoked from the terminal command line. The command must start with awk. The keyword awk is followed by a script that is positioned between quotes. After the quotes, the textfile […]<\/p>\n","protected":false},"author":1,"featured_media":754,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-737","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized"],"_links":{"self":[{"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=\/wp\/v2\/posts\/737","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=737"}],"version-history":[{"count":0,"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=\/wp\/v2\/posts\/737\/revisions"}],"wp:attachment":[{"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=737"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=737"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/archief.van-maanen.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=737"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}