{"id":1146,"date":"2017-10-20T15:15:44","date_gmt":"2017-10-20T20:15:44","guid":{"rendered":"http:\/\/blog.ls-al.com\/?p=1146"},"modified":"2017-10-20T15:16:34","modified_gmt":"2017-10-20T20:16:34","slug":"bash-variable-in-an-awk-search-pattern","status":"publish","type":"post","link":"https:\/\/blog.ls-al.com\/bash-variable-in-an-awk-search-pattern\/","title":{"rendered":"Bash variable in an awk search pattern"},"content":{"rendered":"

I spent some time getting this working so documenting for reference.<\/p>\n

Trying to grab an IP address from a ssh config file works fine using a static string.<\/p>\n

\r\n$ awk '\/^Host rdpclient1$\/{x=1}x&&\/HostName\/{print $2;exit}' ~\/.ssh\/Prod-config\r\n10.1.4.4\r\n<\/pre>\n
Using double quotes and a static variable or double quotes and a bash variable does not work.<\/p>\n
\r\n$ awk "\/^Host rdpclient1$\/{x=1}x&&\/HostName\/{print $2;exit}" ~\/.ssh\/Prod-config\r\n     HostName 10.1.4.4\r\n$ awk "\/^Host $host$\/{x=1}x&&\/HostName\/{print $2;exit}" ~\/.ssh\/Prod-config\r\n     HostName 10.1.4.4\r\n<\/pre>\n
Using double quotes plus a bash variable and escaping the print variable $2 works.<\/p>\n
\r\n$ awk  "\/^Host ${host}$\/{x=1}x&&\/HostName\/{print \\$2;exit}" ~\/.ssh\/Prod-config\r\n10.1.4.4\r\n<\/pre>\n
And an in a little script that use ssh config settings for my RDP through a jumphost or bastion Linux server.<\/p>\n
\r\nHost gw01\r\n     HostName <public IP>\r\n     User opc\r\n     IdentityFile mysshkey\r\nHost rdpclient1\r\n     HostName 10.1.4.4\r\n     ProxyJump gw01\r\n\r\n$ cat rdesktop_jumphost.sh \r\n#!\/bin\/bash\r\nhost=$1\r\nprivateIP=$(awk  "\/^Host ${host}$\/{x=1}x&&\/HostName\/{print \\$2;exit}" ~\/.ssh\/Prod-config)\r\njumphost=$(awk "\/^Host ${host}$\/{x=1}x&&\/ProxyJump\/{print \\$2;exit}" ~\/.ssh\/Prod-config)\r\njumphostIP=$(awk "\/^Host ${jumphost}$\/{x=1}x&&\/HostName\/{print \\$2;exit}" ~\/.ssh\/Prod-config)\r\njumpuser=$(awk "\/^Host ${host}$\/{x=1}x&&\/User\/{print \\$2;exit}" ~\/.ssh\/Prod-config)\r\nlocalRdpPort=33389\r\n\r\nssh -f -N -p 22 -L $localRdpPort:$privateIP:3389 -i mysshkey $jumpuser@$jumphostIP\r\ntunnelpid=$(ps -ef | grep $localRdpPort | grep -v grep | awk '{print $2}')\r\n\r\nrdesktop localhost:$localRdpPort\r\n\r\nkill $tunnelpid\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"
I spent some time getting this working so documenting for reference. Trying to grab an IP address from a ssh<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[93,86,21],"tags":[],"class_list":["post-1146","post","type-post","status-publish","format-standard","hentry","category-awk","category-rdp","category-ssh"],"_links":{"self":[{"href":"https:\/\/blog.ls-al.com\/wp-json\/wp\/v2\/posts\/1146","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.ls-al.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.ls-al.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.ls-al.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.ls-al.com\/wp-json\/wp\/v2\/comments?post=1146"}],"version-history":[{"count":0,"href":"https:\/\/blog.ls-al.com\/wp-json\/wp\/v2\/posts\/1146\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.ls-al.com\/wp-json\/wp\/v2\/media?parent=1146"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.ls-al.com\/wp-json\/wp\/v2\/categories?post=1146"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.ls-al.com\/wp-json\/wp\/v2\/tags?post=1146"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}