匹配后 Bash 打印单词
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Bash print word after match
提问by raphnguyen
I have a variable that stores the output of a file. Within that output, I would like to print the first word after Database:. I'm fairly new to regex, but this is what I've tried so far:
我有一个存储文件输出的变量。在该输出中，我想在Database:. 我对正则表达式相当陌生，但这是我迄今为止尝试过的：
sed -n -e 's/^.*Database: //p' "$output"
When I try this, I am getting a sed: can't read prints_output: File name too longerror.
当我尝试这个时，我收到一个sed: can't read prints_output: File name too long错误。
Does sedonly take in a filename? I am running a hive query to desc formatted tableand storing the results in outputlike so:
是否sed只需要在文件名？我正在运行一个 hive 查询desc formatted table并将结果存储在output像这样：
output=`hive -S -e "desc formatted table"`
outputis then set to the result of that:
output然后设置为结果：
...
# Detailed Table Information
Database: sample_db
Owner: sample_owner
CreateTime: Thu Feb 26 23:36:43 PDT 2015
LastAccessTime: UNKNOWN
Protect Mode: None
Retention: 0
Location: maprfs:/some/location
Table Type: EXTERNAL_TABLE
Table Parameters:
...
回答by Jonathan Leffler
Superficially, you should be using:
从表面上看，您应该使用：
hive -S -e "desc formatted table" |
sed -n -e 's/^.*Database: //p'
This will show the complete line containing Database:. When you've got that working, you can eliminate the unwanted material on the line too.
这将显示包含Database:. 当你开始工作时，你也可以消除线上不需要的材料。
Alternatively, you could use:
或者，您可以使用：
echo "$output" |
sed -n -e 's/^.*Database: //p'
Or, again, given that you're using Bash, you could use:
或者，再一次，假设您使用的是 Bash，您可以使用：
sed -n -e 's/^.*Database: //p' <<< "$output"
I'd use the first unless you need the whole output preserved for rescanning. Then I'd probably capture the output in a file (with tee):
除非您需要保留整个输出以供重新扫描，否则我会使用第一个。然后我可能会在文件中捕获输出（使用tee）：
hive -S -e "desc formatted table" |
tee output.log |
sed -n -e 's/^.*Database: //p'
回答by Potter_nsit
Try using egrep:
尝试使用 egrep：
egrep -oh 'Database:[[:blank:]][[:alnum:]]*[[:blank:]]' <output_file> | awk '{print ;}'
