以静默方式检查 bash 脚本中是否存在 rpm
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Check if rpm exists in bash script silently
提问by Danny
I'm trying to do a quick check to see if an rpm is installed in a bash script using an if statement. But I want to do it silently. Currently, when I run the script, and the rpm does exist, it outputs the output of rpm to the screen which I dont want.
我正在尝试使用 if 语句快速检查 rpm 是否安装在 bash 脚本中。但我想默默地做。目前，当我运行脚本并且 rpm 确实存在时，它会将 rpm 的输出输出到我不想要的屏幕上。
if rpm -qa | grep glib; then
do something
fi
Maybe there is an option to rpm that I am missing? or if I just need to change my statement?
也许有我缺少的 rpm 选项？或者如果我只需要更改我的陈述？
THanks
谢谢
采纳答案by vromanov
1) You can add -q switch to grep
1) 您可以将 -q 开关添加到 grep
if rpm -qa | grep -q glib; then
do something
fi
2) You can redirect stout and/or stderr output to /dev/null
2) 您可以将 Stout 和/或 stderr 输出重定向到 /dev/null
if rpm -qa | grep glib 2>&1 > /dev/null; then
do something
fi
回答by ztank1013
There is the interesting --quietoption available for the rpmcommand. Man page says:
--quiet该rpm命令有一个有趣的选项。手册页说：
--quiet
Print as little as possible - normally only error messages will
be displayed.
So probably you may like to use this one:
所以可能你可能喜欢使用这个：
if rpm -q --quiet glib ; then
do something
fi
This way should be faster because it doesn't have to wait a -qa(query all) rpm packages installed but just queries the target rpm package. Of course you have to know the correct name of the package you want to test if is installed or not.
这种方式应该更快，因为它不必等待-qa（查询所有）安装的 rpm 包，而只是查询目标 rpm 包。当然，您必须知道要测试的软件包是否已安装的正确名称。
Note: using RPM version 4.9.1.2 on fedora 15
注意：在 fedora 15 上使用 RPM 版本 4.9.1.2
回答by user2153517
You need only -q option actually:
您实际上只需要 -q 选项：
$ rpm -q zabbix-agent
package zabbix-agent is not installed
$ rpm -q curl
curl-7.24.0-5.25.amzn1.x86_64
It will look like:
它看起来像：
$ if rpm -q zabbix-agent > /dev/null; then echo "Package zabbix-agent is already installed."; fi
Package zabbix-agent is already installed.
回答by JRFerguson
You could do:
你可以这样做：
[ -z "$(rpm -qa|grep glib)" ] && echo none || echo present
...or, if you prefer:
...或者，如果您愿意：
if [ $(rpm -qa|grep -c glib) -gt 0 ]; then
echo present
else
echo none
fi
回答by ata
You could test if the command returns a string, the command substitution will capture the output:
您可以测试命令是否返回字符串，命令替换将捕获输出：
[[ "$(rpm -qa | grep glib)" ]] && do something
