head
语法
head [options] files
同样也是过滤命令，默认打印每个文档首10行内容。
参数
-
-c | --bytes=[-]NUM显示前NUM个字节的内容。后面如添加了计数单位将会相应改变。-NUM表示出去末尾的个数字节。 -
-n | --lines=[-]NUM显示前NUM行。默认值为10。 -
-q | --quiet | --silent不打印头部显示的文件名。 -
-v | --verbose打印头部显示的文件名。 -
-z | --zero-terminated将所有换行符看做为NUL，不作为新行。 -
--help显示帮助文档。 -
--version显示版本信息。
Example
-
head test默认显示文档前10行内容。
root@3ff83ffc7119:/# head test line1 line2 line3 This is line4 This is line5 This is line6 This is line7 line1 copy line2 copy -
head -n 5 test指定显示行数为开头5行。
root@3ff83ffc7119:/# head -n 5 test line1 line2 line3 This is line4 This is line5 -
head -c 5 test显示指定字节数，单位计量表示
b 512, kB 1000, K 1024, MB 1000*1000, M 1024*1024, GB 1000*1000*1000, G 1024*1024*1024, T, P, E, Z, Y后续亦如此规律。root@3ff83ffc7119:/# head -c 5 test line1root@3ff83ffc7119:/# root@3ff83ffc7119:/# head -c 6 test line1 root@3ff83ffc7119:/# head -c 6k test line1 line2 line3 This is line4 This is line5 This is line6 This is line7 line1 copy line2 copy line3 copy This is line4 copy This is line5 copy This is line6 copy This is line7 copy -
head -v test显示更多的显示信息，
==> test <==这里表示文件名root@3ff83ffc7119:/# head -v -n 5 test ==> test <== line1 line2 line3 This is line4 This is line5 root@3ff83ffc7119:/# head -v test ==> test <== line1 line2 line3 This is line4 This is line5 This is line6 This is line7 line1 copy line2 copy -
head -z test不计算换行。
root@3ff83ffc7119:/# head -z test line1 line2 line3 This is line4 This is line5 This is line6 This is line7 line1 copy line2 copy line3 copy This is line4 copy This is line5 copy This is line6 copy This is line7 copy -
head --version显示当前版本
root@3ff83ffc7119:/# head --version head (GNU coreutils) 8.28 Copyright (C) 2017 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Written by David MacKenzie and Jim Meyering.
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