在linux中使用head命令和tail命令查看文件中的指定行

在linux中使用head命令和tail命令查看文件中的指定行

(2011-04-16 12:20:16)


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标签： 杂谈

分类： Linux

使用head命令和tail命令显示指定的行：

head

-n, --lines=[-]K

print the first K lines instead of the first 10; with the leading

‘-’, print all but the last K lines of each file

tail

-n, --lines=K

output the last K lines, instead of the last 10; or use -n +K to

output lines starting with the Kth

[root@localhost etc]# pwd

/etc

[root@localhost etc]# cat yum.conf

[main]

cachedir=/var/cache/yum/$basearch/$releasever

keepcache=0

debuglevel=2

logfile=/var/log/yum.log

exactarch=1

obsoletes=1

gpgcheck=1

plugins=1

installonly_limit=3

//此处是一空行

# This is the default, if you make this bigger yum won't see if the metadata

# is newer on the remote and so you'll "gain" the bandwidth of not having to

# download the new metadata and "pay" for it by yum not having correct

# information.

# It is esp. important, to have correct metadata, for distributions like

# Fedora which don't keep old packages around. If you don't like this checking

# interupting your command line usage, it's much better to have something

# manually check the metadata once an hour (yum-updatesd will do this).

# metadata_expire=90m

//此处是一空行

# PUT YOUR REPOS HERE OR IN separate files named file.repo

# in /etc/yum.repos.d

[root@localhost etc]# cat yum.conf |wc -l

23

yum.conf文件共有23行

[root@localhost etc]# head yum.conf

[main]

cachedir=/var/cache/yum/$basearch/$releasever

keepcache=0

debuglevel=2

logfile=/var/log/yum.log

exactarch=1

obsoletes=1

gpgcheck=1

plugins=1

installonly_limit=3

显示前10行，这个是默认值

[root@localhost etc]# head -n 2 yum.conf

[main]

cachedir=/var/cache/yum/$basearch/$releasever

显示前2行

[root@localhost etc]# head -n -20 yum.conf

[main]

cachedir=/var/cache/yum/$basearch/$releasever

keepcache=0

显示除最后20行以外的所有行

[root@localhost etc]# tail yum.conf

# download the new metadata and "pay" for it by yum not having correct

# information.

# It is esp. important, to have correct metadata, for distributions like

# Fedora which don't keep old packages around. If you don't like this checking

# interupting your command line usage, it's much better to have something

# manually check the metadata once an hour (yum-updatesd will do this).

# metadata_expire=90m

//此处是一空行

# PUT YOUR REPOS HERE OR IN separate files named file.repo

# in /etc/yum.repos.d

显示最后10行，这是默认值

[root@localhost etc]# tail -n 2 yum.conf

# PUT YOUR REPOS HERE OR IN separate files named file.repo

# in /etc/yum.repos.d

显示最后2行

[root@localhost etc]# tail -n +21 yum.conf

//此处是一空行

# PUT YOUR REPOS HERE OR IN separate files named file.repo

# in /etc/yum.repos.d

从第21行开始显示后面的所有行，即第21行到第23行

显示第11行到第20行(总共23行)：

从第11行开始显示，但不包括最后3行

[huage@localhost etc]$ head -n -3 yum.conf |tail -n +11

显示前20行，但从第11行开始

[huage@localhost etc]$ head -n 20 yum.conf |tail -n +11

显示除最后3行以外的所有行，但只显示最后10行

[huage@localhost etc]$ head -n -3 yum.conf |tail -n 10

显示前20行中的后10行

[huage@localhost etc]$ head -n 20 yum.conf |tail -n 10

从第11行开始显示，但只显示前10行

[huage@localhost etc]$ tail -n +11 yum.conf |head -n 10

从第11行开始显示，但不包括最后3行

[huage@localhost etc]$ tail -n +11 yum.conf |head -n -3

显示最后13行中的前10行

[huage@localhost etc]$ tail -n 13 yum.conf |head -n 10

显示最后13行中除末尾的3行以外的前10行

[huage@localhost etc]$ tail -n 13 yum.conf |head -n -3