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=Tips and tricks=
=Tips and tricks=
==String manipulation==
===Remove character from string===
VERSION='2.3.3'
echo "${VERSION//.}"
===check if var contains substring===
[[ $foo =~ .*sub.* ]]
===get first character of a string===
FIRST=${STRING:0:1}


==read without while loop==
==read without while loop==
Line 20: Line 30:
  if [[ $foo =~ ^[0-9]+$ ]]
  if [[ $foo =~ ^[0-9]+$ ]]


==get first character of a string==
FIRST=${STRING:0:1}


==check if var contains substring==
 
[[ $foo =~ .*sub.* ]]


==move cursor==
==move cursor==

Revision as of 15:25, 22 August 2019

Tips and tricks

String manipulation

Remove character from string

VERSION='2.3.3'
echo "${VERSION//.}"

check if var contains substring

[[ $foo =~ .*sub.* ]]

get first character of a string

FIRST=${STRING:0:1}

read without while loop

The problem is scope, try

echo foo bar | { read a b;echo $b; }

check if variable is integer

if [[ $foo =~ ^[0-9]+$ ]]



move cursor

^b move back 1 char
^f move forward 1 char
alt-b move back 1 word
alf-f move forward 1 word

loops

loop through range of numbers

for i in {0..10};do echo $i;done


bash history timestamp

HISTTIMEFORMAT="%d/%m/%y %T "

screen and bash history

To make sure all screens write to same history (at least on CentOS and RHEL):

echo "history -a;history -r" > /etc/sysconfig/bash-prompt-screen
chmod +x /etc/sysconfig/bash-prompt-screen

In general:

export PROMPT_COMMAND='history -n'

functions

function foo() {
   echo $1 $2
 }