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go-devops

devops based on go

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ps aux output meaning

$ ps aux  
USER       PID  %CPU %MEM  VSZ RSS     TTY   STAT START   TIME COMMAND
timothy  29217  0.0  0.0 11916 4560 pts/21   S+   08:15   0:00 pine  
root     29505  0.0  0.0 38196 2728 ?        Ss   Mar07   0:00 sshd: can [priv]   
can      29529  0.0  0.0 38332 1904 ?        S    Mar07   0:00 sshd: can@notty  

ps aux|head -1 
# Returns: USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND

#ps aux with ppid
ps axo user,pid,ppid,pcpu,pmem,vsz,rss,tname,stat,start,time,args|head -1 
# Returns: USER       PID  PPID %CPU %MEM    VSZ   RSS TTY      STAT  STARTED     TIME COMMAND


# Getting rid of the headers
ps aux --no-heading

# Sorting by pid desc
ps aux --sort=-pid 

# Show with parent/child process tree
ps auxf
Sample Output
root      3279  0.0  0.3  4544 1056 ?        Ss   Feb01   0:00  /usr/sbin/sshd
root      4029  0.0  0.6  8596 2004 ?        Ss   Feb01   0:00  \_ sshd: svcsuprt [priv]
svcsuprt  4032  0.1  0.5  8972 1900 ?        S    Feb01   7:14  |   \_ sshd: svcsuprt@pts/0
svcsuprt  4033  0.0  0.4  6504 1472 pts/0    Ss   Feb01   0:00  |       \_ -bash
svcsuprt 29013  0.0  0.2  2488  768 pts/0    R+   12:04   0:00  |           \_ ps auxf


# ps -aef --forest
root     114032   1170  0 Apr05 ?        00:00:00  \_ sshd: root@pts/4
root     114039 114032  0 Apr05 pts/4    00:00:00  |   \_ -bash
root      56225 114039  0 13:47 pts/4    00:00:16  |       \_ top
root     114034   1170  0 Apr05 ?        00:00:00  \_ sshd: root@notty
root     114036 114034  0 Apr05 ?        00:00:00  |   \_ /usr/libexec/openssh/sftp-server
root     103102   1170  0 Apr06 ?        00:00:03  \_ sshd: root@pts/0
root     103155 103102  0 Apr06 pts/0    00:00:00  |   \_ -bash
root     106798 103155  0 Apr06 pts/0    00:00:00  |       \_ su - postgres
postgres 106799 106798  0 Apr06 pts/0    00:00:00  |           \_ -bash
postgres  60959 106799  0 14:39 pts/0    00:00:00  |               \_ ps -aef --forest
postgres  60960 106799  0 14:39 pts/0    00:00:00  |               \_ more

USER = user owning the process
PID = process ID of the process
%CPU = It is the CPU time used divided by the time the process has been running.
%MEM = ratio of the process’s resident set size to the physical memory on the machine
VSZ = virtual memory usage of entire process (in KiB)
RSS = resident set size, the non-swapped physical memory that a task has used (in KiB)
TTY = controlling tty (terminal)
STAT = multi-character process state
START = starting time or date of the process
TIME = cumulative CPU time
COMMAND = command with all its arguments

Process state codes:

R running or runnable (on run queue)
D uninterruptible sleep (usually IO)
S interruptible sleep (waiting for an event to complete)
Z defunct/zombie, terminated but not reaped by its parent
T stopped, either by a job control signal or because it is being traced

Some extra modifiers:

< high-priority (not nice to other users)
N low-priority (nice to other users)
L has pages locked into memory (for real-time and custom IO)
s is a session leader
l is multi-threaded (using CLONE_THREAD, like NPTL pthreads do)
+ is in the foreground process group

Some scripts

Count cost time of command

#!/bin/bash
START=$(date +%s)

awk 'substr($0,1,19)>="2018-01-04 16:07:18" && substr($0,1,19)<="2018-01-04 16:07:19"' < src.log > cut.log

END=$(date +%s)
DIFF=$(( $END - $START ))
echo "It took $DIFF seconds"

SSH from host1 to host2 without a password on linux

[yogaapp@host1 ~]$ ssh-keygen -t rsa 
[yogaapp@host1 ~]$ ssh-copy-id -i .ssh/id_rsa.pub cpapp@host2

Startup JAVA program

Go program os.Getenv("PATH") print PATH: /usr/local/bin:/bin:/usr/bin, So we need link java executable to /usr/bin or /usr/local/bin.

[root@hitest.app.02 ~]# which java
/opt/jdk1.8.0_20/bin/java
[root@hitest.app.02 ~]# ln -s /opt/jdk1.8.0_20/bin/java /usr/bin/java
[root@hitest.app.02 ~]# ls -l /usr/bin/java
lrwxrwxrwx 1 root root 25 Jan 10 10:56 /usr/bin/java -> /opt/jdk1.8.0_20/bin/java

ls -l command output explanation

From

      +-permissions that apply to the owner
      |
      |     +-permissions that apply to all other users
      |     |
      |     |  +-number of hard links
      |     |  |
      |     |  |             +-size      +-last modification date and time
     _|_   _|_ |            _|__ ________|_______
    drwxr-xr-x 2 ataka root 4096 2008-11-04 16:58 ataka
        ___      _____ ____                       _____
         |         |    |                           |
         |         |    |                           +-name of file or directory
         |         |    |
         |         |    +-the group that the group permissions applies to
         |         |
         |         +-owner
         |
         +-permissions that apply to users who are members of the group
         

Linux中查看各文件夹大小命令

# -h或–human-readable 以K，M，G为单位，提高信息的可读性。
du -h --max-depth=1

Limit log file size.

#!/bin/bash
logfile=$1

# truncate a log-file at 50000 lines.
if [ -f ${logfile} ]
then
    ls -lh ${logfile}
    tail -50000 $logfile > $logfile.tmp
    cat $logfile.tmp > $logfile
    rm $logfile.tmp
    ls -lh ${logfile}
else
    echo "File $logfile not found"
fi

Search log context lines by keyword

#!/bin/awk -f
BEGIN {
    phead = 1 # head of previous lines queue
    ptail = 1 # size of previous lines queue
    pmax = 3 # max size of previous lines queue
    found = 0 # found lines from keyword
    max =  2 # max lines from keyword
}
{
    if (found == 0) {
      if ($0 ~ /7/) {
        found = 1
        for(key in parr) print parr[key]
        print
      } else {
        parr[ptail++] = $0
        if(ptail - phead > pmax) delete parr[phead++]
      }
    } else {
      print
      if(++found == max) exit
    }
}
END {
}

Show top five CPU consuming processes with ps

# n for numeric sorting, r for reverse order and k 2,2 for the second column.
ps aux | sort -nrk 3,3 | head -n 5

# If you want something that's truly 'top'esq with constant updates, use watch
watch "ps aux | sort -nrk 3,3 | head -n 5"

Cron Expression

0 0 8-20 * * ?

CRON Expression Format

A cron expression represents a set of times, using 6 space-separated fields.

Field name	Mandatory?	Allowed values	Allowed special characters
Seconds	Yes	0-59	* / , -
Minutes	Yes	0-59	* / , -
Hours	Yes	0-23	* / , -
Day of month	Yes	1-31	* / , - ?
Month	Yes	1-12 or JAN-DEC	* / , -
Day of week	Yes	0-6 or SUN-SAT	* / , - ?

Predefined schedules

You may use one of several pre-defined schedules in place of a cron expression.

Entry	Description	Equivalent To
@yearly (or @annually)	Run once a year, midnight, Jan. 1st	0 0 0 1 1 *
@monthly	Run once a month, midnight, first of month	0 0 0 1 * *
@weekly	Run once a week, midnight between Sat/Sun	0 0 0 * * 0
@daily (or @midnight)	Run once a day, midnight	0 0 0 * * *
@hourly	Run once an hour, beginning of hour	0 0 * * * *

Intervals

You may also schedule a job to execute at fixed intervals, starting at the time it's added or cron is run. This is supported by formatting the cron spec like this:

@every <duration>

where "duration" is a string accepted by time.ParseDuration.

A duration string is a possibly signed sequence of decimal numbers, each with optional fraction and a unit suffix, such as "300ms", "-1.5h" or "2h45m". Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".

For example, "@every 1h30m10s" would indicate a schedule that activates after 1 hour, 30 minutes, 10 seconds, and then every interval after that.

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