Describe Linux/FindGrepAwkSedXargs here.

Find files containing something in Linux

• https://swcarpentry.github.io/shell-novice/07-find/index.html

• regex only part of grep match returned

Search dir for files containing string and replace all of them

##e.g. search for tentant -> tenant
grep -irlZ 'tentant' ./ |  xargs -0  sed -i 's/tentant/tenant/g'

Delete files older than 30 days

• Check 1st {{[

find /opt/backup -type f -mtime +30 }}}

• Permanently delete ALL the files in folder older thatn 30d

  find /opt/backup -type f -mtime +30 -delete 

• Permanently delte ALL files with a specific extention older than 30d

  find /var/log -name "*.log" -type f -mtime +30 -delete 

• Note when deleting dir's with  -type d  be carefull parent dir might have old modification and everything below will be lost.

Bash loop over files

• Rather than using find and xargs, use globing to find and process files in bash

  • e.g.

    #By enabling the globstar option, you can glob all matching files in this directory and all subdirectories:
    # Make sure globstar is enabled
    shopt -s globstar
    for i in **/*.txt; do # Whitespace-safe and recursive
        process "$i"
    done

awk script to duplicate section under " labels:" of k8s yaml file to " spec: { selector: { matchLables: <...> } }

• Explain
  1. looks for /Deployment/ set f=0
  2. look for /labels:/ but only if f=0, set it to 1
  3. look for /spec:/ only if f=1, increase it and run only if=2, now insert info captured in var a
  4. else save line in a[c++] if f

• Script

  # Reads k8s deployment.yaml, copy the labels: to spec: selector:
  gawk -i inplace '
  { print }
  /Deployment/ { f=0 }
  /labels:/ { if(f == 0) f=1 }
  /spec:/ { if(f == 1) {
      f=f+1
      if (f==2) {
        print "  selector:"
        print "    matchLabels:"
        for(i=2;i<=c;i++) print "  "a[i]
      }
    }
  }
  f{ a[++c]=$0 }
  ' $1

CategoryLinux