小编Mon*_*der的帖子

当我为 java 进程 grep 时，我得到低于输出，但它限制为 4096 个字符，这导致实际进程名称（即 kafka.Kafka）未显示在grep输出中。

这是grep的限制吗？有没有办法打印超过 4096 个限制的字符？

ps -ef | grep java

java -Xmx6G -Xms6G -server -XX:+UseG1GC -XX:MaxGCPauseMillis=20 -XX:InitiatingHeapOccupancyPercent=35 -XX:+DisableExplicitGC -Djava.awt.headless=true -Xloggc:/x/kafka/data01/kafka-app -logs/kafkaServer-gc.log -verbose:gc -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintGCTimeStamps -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.authenticate=false -Dcom. sun.management.jmxremote.ssl=false -Dkafka.logs.dir=/x/kafka/data01/kafka-app-logs -Dlog4j.configuration=file:./../config/log4j.properties -cp :/x /home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/aopalliance-repackaged-2.4.0-b34.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10 -0.10.1.1/bin/../libs/argparse4j-0.5.0.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/connect-api- 0.10.1.1.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/connect-file-0.10.1.1.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/connect-json-0.10.1.1.jar:/ x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/connect-runtime-0.10.1.1.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10- 0.10.1.1/bin/../libs/guava-18.0.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/hk2-api-2.4.0 -b34.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/hk2-locator-2.4.0-b34.jar:/x/home/bmcuser/ kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/hk2-utils-2.4.0-b34.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/ bin/../libs/jackson-annotations-2.6.0.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jackson-core-2.6.3 .jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jackson-databind-2.6.3.jar:/x/home/bmcuser/kafka-paypal/ kafka_2.10-0.10.1.1/bin/../libs/jackson-jaxrs-base-2.6.3.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jackson-jaxrs-json-provider-2.6 .3.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jackson-module-jaxb-annotations-2.6.3.jar:/x/home/ bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/javassist-3.18.2-GA.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/ bin/../libs/javax.annotation-api-1.2.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/javax.inject-1.jar :/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/javax.inject-2.4.0-b34.jar:/x/home/bmcuser/kafka-paypal/ kafka_2.10-0.10.1.1/bin/../libs/javax.servlet-api-3.1.0.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/.. /libs/javax.ws.rs-api-2.0.1.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jersey-client-2.22.2 。罐：/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jersey-common-2.22.2.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10 -0.10.1.1/bin/../libs/jersey-container-servlet-2.22.2.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/ jersey-container-servlet-core-2.22.2.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jersey-guava-2.22.2.jar: /x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jersey-media-jaxb-2.22.2.jar:/x/home/bmcuser/kafka-paypal/kafka_2 .10-0.10.1.1/bin/../libs/jersey-server-2.22.2.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/ jetty-continuation-9.2.15.v20160210.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jetty-http-9.2.15.v20160210.jar: /x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jetty-io-9.2.15.v20160210.jar：/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jetty-security-9.2.15.v20160210.jar:/x/home/bmcuser/kafka-paypal/kafka_2 .10-0.10.1.1/bin/../libs/jetty-server-9.2.15.v20160210.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../ libs/jetty-servlet-9.2.15.v20160210.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jetty-servlets-9.2.15.v20160210。 jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jetty-util-9.2.15.v20160210.jar:/x/home/bmcuser/kafka-paypal /kafka_2.10-0.10.1.1/bin/../libs/jopt-simple-4.9.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/ kafka_2.10-0.10.1.1.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/kafka_2.10-0.10.1.1-so/libs/jetty-server-9.2.15.v20160210.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jetty-servlet-9.2.15.v20160210 .jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jetty-servlets-9.2.15.v20160210.jar:/x/home/bmcuser/kafka- paypal/kafka_2.10-0.10.1.1/bin/../libs/jetty-util-9.2.15.v20160210.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/ ../libs/jopt-simple-4.9.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/kafka_2.10-0.10.1.1.jar:/ x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/kafka_2.10-0.10.1.1-so/libs/jetty-server-9.2.15.v20160210.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jetty-servlet-9.2.15.v20160210 .jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jetty-servlets-9.2.15.v20160210.jar:/x/home/bmcuser/kafka- paypal/kafka_2.10-0.10.1.1/bin/../libs/jetty-util-9.2.15.v20160210.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/ ../libs/jopt-simple-4.9.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/kafka_2.10-0.10.1.1.jar:/ x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/kafka_2.10-0.10.1.1-so/libs/jetty-util-9.2.15.v20160210.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jopt-simple-4.9.jar:/ x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/kafka_2.10-0.10.1.1.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10- 0.10.1.1/bin/../libs/kafka_2.10-0.10.1.1-so/libs/jetty-util-9.2.15.v20160210.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/jopt-simple-4.9.jar:/ x/home/bmcuser/kafka-paypal/kafka_2.10-0.10.1.1/bin/../libs/kafka_2.10-0.10.1.1.jar:/x/home/bmcuser/kafka-paypal/kafka_2.10- …

我正在尝试使用 grep 获取特定模式的最后一个单词或短语。在这个例子中，它将是从最后一个逗号到行尾：

Blah,3,33,56,5,Foo 30,,,,,,,3,Great Value

因此，该行所需的输出将是“超值”。所有行的长度也不同，但在最后一个单词之前总是有一个逗号。

基本上，我想简单地从最后一个逗号输出到行尾。谢谢！

所以我正在测试以下内容：

foo() {  
  printf "\nAll the parameters, each on a separate line:\n"  
  printf "param: %s\n" "$@"  
}  

foo The "nicely colored" rainbow  

输出是：

All the parameters:  
param: The
param: nicely colored
param: rainbow

所以如果我理解正确，因为IFS设置为\t\n我们得到由制表符分隔的参数（ 的第一个字符IFS）。
但是为什么它们被打印在不同的行中？
是为每个参数运行 printf 。即 bash 是否将其转换为 for 循环？
以下（不带双引号）也输出相同的结果：

printf "param: %s\n" $@

我试图将下面的命令（从文件中选择随机行）分配给一个变量，但不起作用。

givinv@87-109:~$ head -$((${RANDOM} % `wc -l < file` + 1)) file | tail -1
cower
givinv@87-109:~$

在我尝试将其分配给变量时遇到的错误下方。

givinv@87-109:~$ VARIA=`head -$((${RANDOM} % `wc -l < file` + 1)) file | tail -1`
bash: command substitution: line 1: unexpected EOF while looking for matching `)'
bash: command substitution: line 2: syntax error: unexpected end of file
bash: command substitution: line 1: syntax error near unexpected token `)'
bash: command substitution: line 1: ` + 1)) file | tail -1'
-l: command …

我在终端中使用屏幕和分离模式运行 sleep 命令。
一旦屏幕立即返回，我就会运行ps命令来验证睡眠是否正在运行。

$ screen -d -m 'sleep 2m'
[raj@localhost ~]$ ps
PID TTY          TIME CMD
22795 pts/0    00:00:00 bash
22869 pts/0    00:00:00 ps

但是命令没有显示睡眠。我在这里做错了什么？

我正在使用 grep 解析文件，屏幕上的输出包含换行符，如下所示：

$ grep 'gene' sequence.gb
     gene            89..1483
                     /gene="non-structural protein"
                     /gene="non-structural protein"
                     /gene="non-structural protein"
                     /gene="non-structural protein"
                     /gene="non-structural protein"
                     /gene="non-structural protein"
                     /gene="non-structural protein"
     gene            complement(1987..2763)
                     /gene="nucleocapsid protein"
                     /gene="nucleocapsid protein"

我可以将它分配给一个变量并用换行符打印出来：

$ gene=$(grep 'gene' sequence.gb)
echo "$gene"
     gene            89..1483
                     /gene="non-structural protein"
                     /gene="non-structural protein"
                     /gene="non-structural protein"
                     /gene="non-structural protein"
                     /gene="non-structural protein"
                     /gene="non-structural protein"
                     /gene="non-structural protein"
     gene            complement(1987..2763)
                     /gene="nucleocapsid protein"
                     /gene="nucleocapsid protein"

但这不包含真正的换行符，因为如果我再次 grep 包含 '..' 的行，我会得到很多：

$ echo "$gene" | grep '..'
     gene            89..1483
                     /gene="non-structural protein"
                     /gene="non-structural protein"
                     /gene="non-structural protein"
                     /gene="non-structural protein"
                     /gene="non-structural …