{"id":10806,"date":"2024-12-12T06:33:56","date_gmt":"2024-12-12T06:33:56","guid":{"rendered":"https:\/\/blog.trustedhosting.in\/?p=10806"},"modified":"2024-12-12T06:33:56","modified_gmt":"2024-12-12T06:33:56","slug":"how-to-read-and-edit-files-in-linux","status":"publish","type":"post","link":"https:\/\/www.webystrata.com\/blog\/how-to-read-and-edit-files-in-linux\/","title":{"rendered":"How to Read and Edit Files in Linux"},"content":{"rendered":"

\"How<\/a><\/h1>\n

How to Read and Edit Files in Linux<\/h1>\n

This guide is only going to show an overview of the commands. To find out more about each command you can run the following:<\/p>\n

\n
\n
man [<\/span>command]<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
There are several ways to output a file in Linux<\/a>.<\/p>\n
Here are two test files and their content, we\u2019ll be using these in the upcoming examples.<\/p>\n
\n
\n
cat fileone.txt\r\n<\/pre>\n<\/div>\n<\/div>\n
\n
\n
one<\/span>\r\ntwo<\/span>\r\nthree<\/span>\r\nfour<\/span>\r\nfive<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
\n
\n
cat filetwo.txt\r\n<\/pre>\n<\/div>\n<\/div>\n
\n
\n
ONE<\/span>\r\nTWO<\/span>\r\nTHREE<\/span>\r\nFOUR<\/span>\r\nFIVE<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
\n
cat<\/span><\/code><\/h2>\n
cat<\/span><\/code>\u00a0is mostly used today to output a file to the screen.<\/p>\n
\n
\n
[root@c7 ~]# <\/span>cat fileone.txt\r\none<\/span>\r\ntwo<\/span>\r\nthree<\/span>\r\nfour<\/span>\r\nfive<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
It was originally to combine the output of two files.<\/p>\n
\n
\n
[root@c7 ~]# <\/span>cat fileone.txt filetwo.txt\r\none<\/span>\r\ntwo<\/span>\r\nthree<\/span>\r\nfour<\/span>\r\nfive<\/span>\r\nONE<\/span>\r\nTWO<\/span>\r\nTHREE<\/span>\r\nFOUR<\/span>\r\nFIVE<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
It can be used to add content to a file.<\/p>\n
\n
\n
[root@c7 ~]# <\/span>cat > filethree.txt\r\nnew file content<\/span>\r\n^C<\/span>\r\n[root@c7 ~]# <\/span>cat filethree.txt\r\nnew file content<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
After the\u00a0cat<\/span>\u00a0><\/span>\u00a0filethree.txt<\/span><\/code>\u00a0command, press enter and enter the text you want to add to your file. End this with a new line and\u00a0ctrl<\/span>\u00a0+<\/span>\u00a0c<\/span><\/code>.<\/p>\n
\n
This command will\u00a0NOT<\/strong>\u00a0tell you if the file already exists so it\u2019s very easy to overwrite a file. Use with care.<\/p>\n<\/div>\n<\/section>\n
\n
`less<\/h2>\n
For<\/span>\u00a0very<\/span>\u00a0large<\/span>\u00a0files<\/span>\u00a0less<\/span>\u00a0will<\/span>\u00a0allow<\/span>\u00a0you<\/span>\u00a0to<\/span>\u00a0scroll<\/span>\u00a0up<\/span>\u00a0and<\/span>\u00a0down<\/span>\u00a0a<\/span>\u00a0file.<\/span>\u00a0Search<\/span>\u00a0the<\/span>\u00a0file<\/span>\u00a0with<\/span>\u00a0the<\/span><\/code>\/searchtermkeys.<\/span>\u00a0Use<\/span>\u00a0the<\/span><\/code>n` key to keep searching.<\/p>\n<\/section>\n
\n
head<\/span><\/code><\/h2>\n
By default\u00a0head<\/span><\/code>\u00a0will show the top 10 lines of a file. This can be adjusted with the\u00a0-n<\/span><\/code>\u00a0flag.<\/p>\n
\n
\n
[root@c7 ~]# <\/span>head -n 2<\/span> fileone.txt\r\none<\/span>\r\ntwo<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n<\/section>\n
\n
tail<\/span><\/code><\/h2>\n
By default\u00a0tail<\/span><\/code>\u00a0will show the bottom 10 lines of a file. This can adjusted with the\u00a0-n<\/span><\/code>\u00a0flag.<\/p>\n
\n
\n
[root@c7 ~]# <\/span>tail -n 2<\/span> fileone.txt\r\nfour<\/span>\r\nfive<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n
If your file is changing, you can watch the output. This is best used on logs like mail logs.<\/p>\n
\n
\n
[root@c7 ~]# <\/span>tail -f \/var\/log\/maillog\r\nAug 10 00:00:21 c7 sSMTP[31684]: Unable to locate mail<\/span>\r\nAug 10 00:00:21 c7 sSMTP[31684]: Cannot open mail:25<\/span>\r\nAug 10 11:10:44 c7 postfix\/postqueue[23404]: fatal: Cannot flush mail queue - mail system is down<\/span>\r\nAug 10 11:10:54 c7 postfix\/postfix-script[23546]: starting the Postfix mail system<\/span>\r\nAug 10 11:10:54 c7 postfix\/master[23548]: daemon started -- version 2.10.1, configuration \/etc\/postfix<\/span>\r\nAug 11 00:00:07 c7 sSMTP[25365]: Unable to locate mail<\/span>\r\nAug 11 00:00:07 c7 sSMTP[25365]: Cannot open mail:25<\/span>\r\nAug 11 11:17:21 c7 postfix\/smtpd[9292]: connect from localhost[::1]<\/span>\r\nAug 11 11:18:32 c7 postfix\/smtpd[9292]: lost connection after CONNECT from localhost[::1]<\/span>\r\nAug 11 11:18:32 c7 postfix\/smtpd[9292]: disconnect from localhost[::1]<\/span><\/pre>\n<\/div>\n<\/div>\n<\/section>\n","protected":false},"excerpt":{"rendered":"
How to Read and Edit Files in Linux This guide is only going to show an overview of the commands.…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[],"class_list":["post-10806","post","type-post","status-publish","format-standard","hentry","category-linux"],"_links":{"self":[{"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/posts\/10806","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/comments?post=10806"}],"version-history":[{"count":3,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/posts\/10806\/revisions"}],"predecessor-version":[{"id":10810,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/posts\/10806\/revisions\/10810"}],"wp:attachment":[{"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/media?parent=10806"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/categories?post=10806"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.webystrata.com\/blog\/wp-json\/wp\/v2\/tags?post=10806"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}