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Useful Commands

Bash

Display the access rights in octal of all files with in a directory

stat -c "%a %n" *

Diffing a local and remote file.

  • The diff utility can take one operand in the form of stdin (represented by "-")
ssh node1.example.com cat '/full/file/path/text.txt' | diff -y --suppress-common-lines /full/file/path/text.txt -

Diff two remote files

  • The diff utility can take one operand in the form of stdin (represented by "-")
diff -y --suppress-common-lines <(ssh node1.example.com 'cat /full/file/path/text.txt') <( ssh node2.example.com 'cat /full/file/path/text.txt')

Sort files by human readable size

du -sk * | sort -rn | awk '{print $2}' | xargs -ia du -hs "a"
du -sk * | sort -rn | awk '{ split( "KB MB GB" , v ); s=1; while( $1>1024 ){ $1/=1024; s++ } print int($1) v[s], $2 }'
sudo du -sk .[!.]* * | sort -rn | awk '{ split( "KB MB GB" , v ); s=1; while( $1>1024 ){ $1/=1024; s++ } print int($1) v[s], $2 }'

Determine Inode Usage Don't expect this to run quickly...

In a directory where you suspect there might be a lot of inode usage run the following

find . -type d |
while
  read line
do
  echo "$( find "$line" -maxdepth 1 | wc -l) $line"
done |
sort -rn | less

Test GPG Passphrase

echo "1234" | gpg --no-use-agent -o /dev/null --local-user <keyID> -as - && echo "The correct passphrase was entered for this key"

List Linux processes using SWAP memory

for file in /proc/*/status ; do awk '/VmSwap|Name/{printf $2 " " $3}END{ print ""}' $file; done | sort -k 2 -n -r | less

List the free PV disk space not used by LVM

freepe=$(sudo pvdisplay | grep 'Free PE' | awk '{ print $3 }') && pesize=$(sudo pvdisplay | grep 'PE Size' | awk '{ print int( $3 ) }') && mbpe=$(expr ${freepe} \* ${pesize}) && echo $(expr ${mbpe} / 1024) GB

Awk

Sed

Update multiple files with find + sed

Remove lines matching pattern(gimmick) from multiple files

find . -name "*.md" -type f | xargs -o sed -i '' '/gimmick/d'

VIM

Delete lines that do contain a word/pattern

:%g/price/d

Delete lines that do NOT contain a word/pattern

:%g!/price/d