Quickly Locate Errors in Embedded Development Logs

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Source | CSDN-nan1996
Compiled & formatted | Embedded Application Research Institute

Quickly Locate Errors in Large Log Files

View logs dynamically

tail -f catalina.out

Open the log file from the beginning

cat catalina.out

You can use >nanjiangtest.txt to output a new log for viewing

[root@yesky logs]# cat -n catalina.out | grep 717892466 > nanjiangtest.txt

Simple Commands for tail/head:

[root@yesky logs]# tail -n number catalina.out Get the last number lines of the log
        [root@yesky logs]# tail -n +number catalina.out Get all logs after line number
        [root@yesky logs]# head -n number catalina.out Get the first number lines of the log file
        [root@yesky logs]# head -n -number catalina.out Get all logs except the last number lines

Method 1 (Find line numbers by keywords):

Using grep to get very few logs, we need to check nearby logs. I do this by first: cat -n test.log | grep "keyword" to get the line number of the key log

[root@yesky logs]# cat -n catalina.out | grep 717892466
13230539        [11:07 17:47:11] INFO nanjiang:Edit Old Article: 717892466-2020-11-07 17:47:11
13230593        [11:07 17:47:15] INFO nanjiangSave Article ID IS: 717892466
13230595        717892466 article.getDisplayTime()1 = 2020-11-07 16:25:11
13230596        717892466 article.getDisplayTime()2 = 2020-11-07 16:25:11
13230601        [11:07 17:47:15] INFO nanjiang 10.10.10.39 edit article 717892466 Edit article

“cat -n catalina.out | tail -n +13230539 | head -n 10”

  • tail -n +13230539 means to query logs after line 13230539
  • head -n 10 means to query the first 10 records from the previous query result
[root@yesky logs]# cat -n catalina.out | tail -n +13230539 | head -n 10
13230539        [11:07 17:47:11] INFO nanjiang:Edit Old Article: 717892466-2020-11-07 17:47:11
13230540        [11:07 17:47:11] INFO Takes:2 ms class com.tmg.cms.manager.dao.article.impl.ArticleContentDaoImpl getListByArticleId [NzE3ODkyNDY2] [int]
13230541        [11:07 17:47:11] INFO Takes:1 ms class com.tmg.cms.manager.dao.resourceImage.impl.ResourceImageDaoImpl load
13230542        [11:07 17:47:11] INFO Takes:0 ms class com.tmg.cms.manager.dao.resourceImage.impl.ResourceImageDaoImpl load
13230543        [11:07 17:47:11] INFO Takes:1 ms class com.tmg.cms.manager.dao.resourceImage.impl.ResourceImageDaoImpl load
13230544        [11:07 17:47:11] INFO article.getImage3: /uploadImages/2020/312/02/3NXCRK4U3589_2.jpg
13230545        [11:07 17:47:11] INFO Takes:0 ms class com.tmg.cms.manager.dao.resourceImage.impl.ResourceImageDaoImpl load
13230546        [11:07 17:47:11] INFO Takes:2 ms class com.tmg.cms.manager.dao.privilege.impl.UserDaoImpl getUserByid
13230547        [11:07 17:47:11] INFO Takes:57 ms class com.tmg.cms.manager.dao.sitemap.impl.SitemapDaoImpl selectSitemapWithoutAudit [MQ==] [int]
13230548        [11:07 17:47:11] INFO Takes:5 ms class com.tmg.cms.manager.dao.forbidword.impl.ForbidwordDaoImpl getForbidwordBysiteid [MjI=] [int]

Method 2: View logs within a specified time range

First, check if there are logs within the current day by querying the time range

grep '11:07 18:29:20' catalina.out
grep '11:07 18:31:11' catalina.out

Query within the time range

sed -n '/11:07 18:29:20/,/11:07 18:31:11/p' catalina.out
sed -n '/11:07 18:29:/,/11:07 18:31:/p' catalina.out

Method 3: Count occurrences of specific characters in logs

[root@yesky logs]# grep '1175109632' catalina.out | wc -l
154

Method 4: Query the last number of lines and find the keyword “result”

[root@yesky logs]# tail -n 20 catalina.out | grep 'INFO Takes:1'
[11:11 22:02:51] INFO Takes:1 ms class com.tmg.cms.manager.dao.config.impl.ConfigInfoDaoImpl load
[11:11 22:02:51] INFO Takes:1 ms class com.tmg.cms.manager.dao.sitemap.impl.SitemapDaoImpl getSitemapTop [NTkwOTQ5] [int]
[11:11 22:02:51] INFO Takes:1 ms class com.tmg.cms.manager.dao.sitemap.impl.SitemapDaoImpl getSitemapTop [MzI0] [int]
[11:11 22:02:51] INFO Takes:1 ms class com.tmg.cms.manager.dao.sitemap.impl.SitemapDaoImpl getSitemapTop [MzI3] [int]
[11:11 22:02:51] INFO Takes:1 ms class com.tmg.cms.manager.dao.sitemap.impl.SitemapDaoImpl getSitemapTop [MzMw] [int]
[11:11 22:02:51] INFO Takes:1 ms class com.tmg.cms.manager.dao.sitemap.impl.SitemapDaoImpl getSitemapTop [MzA5NA==] [int]
[11:11 22:02:51] INFO Takes:1 ms class com.tmg.cms.manager.dao.sitemap.impl.SitemapDaoImpl getSitemapTop [NTQ2MzQw] [int]
[11:11 22:02:51] INFO Takes:1 ms class com.tmg.cms.manager.dao.sitemap.impl.SitemapDaoImpl getSitemapTop [NTg2NzYy] [int]
[11:11 22:02:51] INFO Takes:1 ms class com.tmg.cms.manager.dao.sitemap.impl.SitemapDaoImpl getSitemapTop [MzYyMjA=] [int]

Method 5: Query the last number of lines, find the keyword “result” and highlight the results

[root@yesky logs]# tail -n 20 catalina.out | grep 'INFO Takes:1' --color
[11:11 22:02:51] INFO Takes:1 ms class com.tmg.cms.manager.dao.config.impl.ConfigInfoDaoImpl load
[11:11 22:02:51] INFO Takes:1 ms class com.tmg.cms.manager.dao.sitemap.impl.SitemapDaoImpl getSitemapTop [NTkwOTQ5] [int]
[11:11 22:02:51] INFO Takes:1 ms class com.tmg.cms.manager.dao.sitemap.impl.SitemapDaoImpl getSitemapTop [MzI0] [int]

Method 6: Query the last number of lines, find the keyword “result”, highlight the results, and expand two lines above and below

[root@yesky logs]# tail -n 20 catalina.out | grep 'INFO Takes:1' --color -a2
[11:11 22:02:51] INFO Takes:0 ms class com.tmg.cms.manager.dao.article.impl.ArticleContentDaoImpl getArticlePageNum [NzE4MTM2ODky] [int]
[11:11 22:02:51] INFO Takes:1 ms class com.tmg.cms.manager.dao.config.impl.ConfigInfoDaoImpl load [com.tmg.cms.manager.model.config.ConfigInfo]

Method 7: Paginated view, use space to flip pages (using more/less)

[root@yesky logs]# tail -n 2000 catalina.out | grep 'INFO Takes:1' --color -a2 | more
        [root@yesky logs]# tail -n 2000 catalina.out | grep 'INFO Takes:1' --color -a2 | less

Additional

1. Full screen navigation
  • ctrl + F – Move forward one screen
  • ctrl + B – Move back one screen
  • ctrl + D – Move forward half a screen
  • ctrl + U – Move back half a screen
2. Single line navigation
  • j – Move forward one line
  • k – Move back one line
3. Other navigation
  • G – Move to the last line
  • g – Move to the first line
  • q / ZZ – Exit less command
———— END ————
Quickly Locate Errors in Embedded Development Logs
● Column “Embedded Tools”
● Column “Embedded Development”
● Column “Keil Tutorial”
● Selected Tutorials in Embedded Column
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