$ cat testfile #testfile原来的内容 Linux networks are becoming more and more common,
but scurity is often an overlooked
issue.Unfortunately,in today’s environment all networks
are potential hacker targets,
fro0m tp-secret military research networks to small home LANs.LinuxNetworkSecurty focuses on securing Linuxin a
networked environment,where the
security of the entire network needs to be considered
rather than just isolated machines.It uses a mix of theory and practicl techniques to
teach administrators how to install anduse security applications,as well as how the
applcations work and why they are necesary.
使用 tr 命令大小写转换后，得到如下输出结果：
$ cat testfile | tr a-z A-Z #转换后的输出
LINUX NETWORKS ARE BECOMING MORE AND MORE COMMON, BUT SCURITY IS OFTEN AN OVERLOOKED
ISSUE. UNFORTUNATELY, IN TODAY’S ENVIRONMENT ALL NETWORKS ARE POTENTIAL HACKER TARGETS,
FROM TP-SECRET MILITARY RESEARCH NETWORKS TO SMALL HOME LANS.
LINUX NETWORK SECURTY FOCUSES ON SECURING LINUX IN A NETWORKED ENVIRONMENT, WHERE THE
SECURITY OF THE ENTIRE NETWORK NEEDS TO BE CONSIDERED RATHER THAN JUST ISOLATED MACHINES.
IT USES A MIX OF THEORY AND PRACTICL TECHNIQUES TO TEACH ADMINISTRATORS HOW TO INSTALL AND
USE SECURITY APPLICATIONS, AS WELL AS HOW THE APPLCATIONS WORK AND WHY THEY ARE NECESARY.
大小写转换，也可以通过[:lower][:upper]参数来实现。例如使用如下命令：
cat testfile |tr [:lower:][:upper:]
输出结果如下：
$ cat testfile | tr [:lower:][:upper:]#转换后的输出
LINUX NETWORKS ARE BECOMING MORE AND MORE COMMON, BUT SCURITY IS OFTEN AN OVERLOOKED
ISSUE. UNFORTUNATELY, IN TODAY’S ENVIRONMENT ALL NETWORKS ARE POTENTIAL HACKER TARGETS,
FROM TP-SECRET MILITARY RESEARCH NETWORKS TO SMALL HOME LANS.
LINUX NETWORK SECURTY FOCUSES ON SECURING LINUX IN A NETWORKED ENVIRONMENT, WHERE THE
SECURITY OF THE ENTIRE NETWORK NEEDS TO BE CONSIDERED RATHER THAN JUST ISOLATED MACHINES.
IT USES A MIX OF THEORY AND PRACTICL TECHNIQUES TO TEACH ADMINISTRATORS HOW TO INSTALL AND
USE SECURITY APPLICATIONS, AS WELL AS HOW THE APPLCATIONS WORK AND WHY THEY ARE NECESARY.
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