How to replace tab with newline:

gz@linux:~$ cat list
str1    str2    str3    str4    str5    str6    str7    str8
gz@linux:~$ cat list | tr '\t' '\n' >list2
gz@linux:~$ cat list2
str1
str2
str3
str4
str5
str6
str7
str8

How to get different parts of a string, for example with path and file name:

gz:tips# foo=/tmp/dir/filename.tar.gz
gz:tips# echo ${foo%/*}
/tmp/dir
gz:tips# echo ${foo##*/}
filename.tar.gz
gz:tips# echo ${foo%%.*}
/tmp/dir/filename
gz:tips# echo ${foo%.tar.gz}
/tmp/dir/filename
gz:tips# echo ${foo#*.}
tar.gz

How to rename multiple files, same name and different extension:

In this example below, I need to rename all win11* files into win11usb*.

fmbp16:win11usb.vmwarevm $ ls win11*
win11.nvram	win11.plist	win11.vmsd	win11.vmx	win11.vmxf
fmbp16:win11usb.vmwarevm $ for i in $(ls win11*); do mv ${i} win11usb.${i#*.}; done
fmbp16:win11usb.vmwarevm $ ls win11*
win11usb.nvram	win11usb.plist	win11usb.vmsd	win11usb.vmx	win11usb.vmxf
fmbp16:win11usb.vmwarevm $

How to find and rename recursively. First example is for files and second for directories:

gz:tips# for FILE in $(find . -type f -name "*foo*"); do NEW=`echo $FILE | sed -e 's/foo/bar/'`; mv "$FILE" "$NEW"; done
gz:tips# for DIR in $(find . -type d -name "*foo*"); do NEW=`echo $DIR | sed -e 's/foo/bar/'`; mv "$DIR" "$NEW"; done

How to display with awk from a desired column to the end. In the examples below we will display the free space for all vgs in AIX system:

root@gzaix:~# [color=green]for i in $(lsvg -o); do printf "$i ==>\t";lsvg $i| grep -i free| awk '{ print substr($0, index($0,$4)) }'; done[/color]
datavg06 ==>    FREE PPs:       3 (384 megabytes)
datavg ==>      FREE PPs:       489 (62592 megabytes)
datavg01 ==>    FREE PPs:       549 (70272 megabytes)
datavg04 ==>    FREE PPs:       4 (512 megabytes)
datavg03 ==>    FREE PPs:       109 (13952 megabytes)
datavg02 ==>    FREE PPs:       159 (20352 megabytes)
datavg07 ==>    FREE PPs:       4 (256 megabytes)
datavg08 ==>    FREE PPs:       125 (8000 megabytes)
datavg05 ==>    FREE PPs:       143 (18304 megabytes)
rootvg ==>      FREE PPs:       13 (1664 megabytes)

How to search for a string in multiple files on linux:

root@linux:~# find . -type f -print0 | xargs -0 grep -i book

How to search and replace a string in multiple files on linux:

root@linux:~# find . -type f -print0 | xargs -0 sed -i 's/book/BOOK/g'

How to search for directories with a specific number of files inside:

FILESCOUNT="1"; find . -maxdepth 1 -type d -exec bash -c "echo -ne ‘{}’; ls ‘{}’ | wc -l" \; | awk -v fc="$FILESCOUNT" ‘$NF==fc {print $0} END {print "The dirs above have " fc " files inside."}’

How to display the last column from an output:

root@aix:/ # lssrc -s nimsh
Subsystem         Group            PID          Status
 nimsh            nimclient                     inoperative
root@aix:/ # lssrc -s nimsh | awk '{print $NF}'
Status
inoperative

How to extract only numbers from a string with bash:

root@linux:~# [color=green]TEST="1238ksds98amnsa62knb2gi2v23v"[/color]
root@linux:~# [color=green]echo ${TEST//[!0-9]/}[/color]
123898622223
root@linux:~# [color=green]echo ${TEST//[^0-9]/}[/color]
123898622223

How to extract only numbers from a string with sed:

root@linux:~# [color=green]echo 1238ksds98amnsa62knb2gi2v23v | sed 's/[^0-9]//g'[/color]
123898622223

Passing variable to awk:

root@linux:~# [color=green]for i in 21684 26667 20991; do ps -ef | awk -v ss="$i" '$2 ~ ss { print }'; done[/color]
root     21684 10157  0 Nov22 tty1     00:00:00 -bash
root     26667     1  0 Nov22 ?        00:00:00 dhclient3 eth2
vbox     20991 20983  0 Oct24 ?        00:00:00 gnome-session

another example:

florian@florian:~$ [color=green]for i in 1 2 3 4 5; do echo $i | awk -v ss="awkvar$i" '{print ss" from "$0}'; done[/color]
awkvar1 from 1
awkvar2 from 2
awkvar3 from 3
awkvar4 from 4
awkvar5 from 5

How to count a string's characters:

root@linux:~$ STRING="12345"
root@linux:~$ echo "Chars: ${#STRING}"
Chars: 5

How to remove blank lines from a file using grep and awk:

root@linux:~# cat /tmp/test.txt
1234567890

abcde
fgh

ijklmn

root@linux:~# grep -v ^$ /tmp/test.txt
1234567890
abcde
fgh
ijklmn

root@linux:~# awk 'NF != 0 {print} ' /tmp/test.txt
1234567890
abcde
fgh
ijklmn

How to add a line after some string

(to add "BOOOOOOO!" if the line contains "abc" (first example) or if the line is "fgh" (second example)):

root@linux:~# awk '{print ; if ($0 ~ "abc") print "BOOOOOOO!"}' /tmp/test.txt
1234567890

abcde
BOOOOOOO!
fgh

ijklmn

root@linux:~# awk '{print ; if ($0 == "fgh") print "BOOOOOOO!"}' /tmp/test.txt
1234567890

abcde
fgh
BOOOOOOO!

ijklmn

How to transform a line from lowercase to uppercase with sed:

root@linux:~# sed 's/abcde/ABCDE/g' /tmp/test.txt
1234567890

ABCDE
fgh

ijklmn

How to split a string after the second delimiter with sed:

gz@linux:~$ echo "1:2:3:4:5:6:7:8:9" | sed "s/\([^:]*:[^:]*\):/\1\n/g"
1:2
3:4
5:6
7:8
9

or

gz@linux:~$ echo "1:2:3:4:5:6:7:8:9" | sed "s/[^:]*:[^:]*:/& /g" | sed "s/: /\n/g" 
1:2
3:4
5:6
7:8
9

or in ksh

gz@aix~# echo "1:2:3:4:5:6:7:8:9" | sed "s/\([^:]*:[^:]*\):/\1 /g" | tr " " "\n"
1:2
3:4
5:6
7:8
9

How to replace the 3rd same (repetitive) character with another:

srt@gz$ echo "00:21:26:400 --> 00:21:28:400" | sed "s/\([^00:]*:[^:]*:[^:]*\):/\1\,/g"
00:21:26,400 --> 00:21:28,400

How to convert uppercase to lowercase characters in a file with TR:

florian@florian:~$ cat b
ASLDJSLDJSLKJD
SLKJDLKSJDLK
SOIDUSOIDUOIS
SDOSDSJLD
florian@florian:~$ cat b | tr '[:upper:]' '[:lower:]' 
asldjsldjslkjd
slkjdlksjdlk
soidusoiduois
sdosdsjld
florian@florian:~$ cat b | tr '[A-Z]' '[a-z]'  
asldjsldjslkjd
slkjdlksjdlk
soidusoiduois
sdosdsjld

How to rename filenames in different order (for example files like "This is file 001.jpg" to "001 file is This.jpg"):

1. Put them to a file like ls.txt.
2. Run this script in the same directory.

#!/bin/bash
#
cat ls.txt | sed s/.jpg//g | while read line;
  do
	arr=($line)
	mv "${arr[0]} ${arr[1]} ${arr[2]} ${arr[3]}.jpg" "${arr[3]} ${arr[2]} ${arr[1]} ${arr[0]}.jpg"
done

How to calculate and display in AIX disk space in GB:

Total from bootinfo:

root@aix:~# [color=green]for i in $(lspv|awk '{print $1}' | xargs); do bootinfo -s $i; done | awk '{ s = s+$1/1024 } END { printf "Total disk space: %dGB\n",s }'[/color]
Total disk space: 4125GB

Total from lsvg info:

root@aix:~# [color=green]for i in $(lsvg -o); do lsvg $i| grep -i total| awk '{ print substr($0, index($0,$7)) }'; done | sed "s/[^0-9]//g" | awk '{ s = s+$1/1024 } END { printf "Total: %dGB\n",s }'[/color]
Total: 559GB

Total used and free from lsvg info:

root@aix:~# [color=green]for i in $(lsvg -o); do lsvg $i| grep -i free| awk '{ print substr($0, index($0,$7)) }'; done | sed "s/[^0-9]//g" | awk '{ s = s+$1/1024 } END { printf "Free: %dGB\n",s }'[/color]
Free: 20GB
root@aix:~# [color=green]for i in $(lsvg -o); do lsvg $i| grep -i used| awk '{ print substr($0, index($0,$6)) }'; done | sed "s/[^0-9]//g" | awk '{ s = s+$1/1024 } END { printf "Used: %dGB\n",s }'[/color]
Used: 538GB

How to search for files which contains a specific text within a tar archive:

root@aix:~# [color=green]for f in `ls archives*.tar.Z `; do echo $f; zcat $f | tar -tvf - | grep WHAT_TO_SEARCH_FOR; done;[/color]
archives_20141007.tar.Z
archives_20141006.tar.Z
archives_20141009.tar.Z
-rw-rw-r-- 35000 3500    3120 Oct 06 15:00:05 2014 ./00/THE_FILE_INSIDE_ARCHIVE_WHICH_CONTAINS_WHAT_YOU_ARE_SEARCHIG_FOR

How to display the archives which have files with a specific text inside:

root@aix:~# ls archives*.tar.Z
archives_20141007.tar.Z
archives_20141006.tar.Z
archives_20141009.tar.Z
root@aix:~# [color=green]./test.sh "archives*.tar.Z" WHAT_TO_SEARCH_FOR[/color]
archives_20141009.tar.Z

The script:

root@aix:~# cat test.sh
STRING=$2
FILE=$1

if [ -z  "$STRING" ]; then
        echo "What are you looking for?"
        exit 99
fi

for f in $(ls ${FILE});
        do
        zcat $f | tar -tvf - | grep ${STRING} >/dev/null 2>&1;
        RC=$?
        if [ $RC == 0 ]; then
        echo $f
        fi
done

How to remove all whitespace (including tabs) from the beginning of the line to the first word:

# echo " Test, BABY!" | sed -e 's/^[ \t]*//'

How to change the extension on files in bulk with rename command:

# find . -name "*.php5" -exec rename -f 's/\.php5/.php/' {} \;

How to remove the extension on files in bulk with rename command:

# find . -name "*.php5" -exec rename -f 's/\.php5/.php/' {} \;

How to print field number X only on lines matching something, otherwise print field number Y with awk:

In this example below, as you can see, I am using the same awk command to print the field I want: virtual disk path

vbox@core:~$ vbm showvminfo irc | grep ^SATA | grep -v Empty
SATA (0, 0): /home/vbox/.VirtualBox/dynamic/irc/irc.vdi (UUID: 6e9e97ff-f312-45ca-8b3e-fa18b9032dd0)
vbox@core:~$ [color=green]vbm showvminfo irc | grep ^SATA | grep -v Empty | [/color][color=yellow]awk '/Controller/{print $5;next}{print $4}'[/color]
/home/vbox/.VirtualBox/dynamic/irc/irc.vdi

vbox@core:~$ vbm showvminfo egg | grep ^SATA | grep -v Empty
SATA Controller (0, 0): /home/vbox/.VirtualBox/dynamic/egg/egg.vdi (UUID: 6977dea1-e224-4d04-8649-b688baed2430)
SATA Controller (1, 0): /home/vbox/.VirtualBox/dynamic/egg/egg-swap.vdi (UUID: 5b039f89-ed53-4ce8-809b-9aeb84273b36)
vbox@core:~$ [color=green]vbm showvminfo egg | grep ^SATA | grep -v Empty | [/color][color=yellow]awk '/Controller/{print $5;next}{print $4}'[/color]
/home/vbox/.VirtualBox/dynamic/egg/egg.vdi
/home/vbox/.VirtualBox/dynamic/egg/egg-swap.vdi

How to find out which lines from one file are missing from another:

10:45:41 root@sonic:tmp# cat a
1
2
3
4
5
10:45:50 root@sonic:tmp# cat b
1
2
3
4
5
6
7
8
9
10
10:45:53 root@sonic:tmp# grep -F -v -x -f a b
6
7
8
9
10