Bash: Difference between revisions

From DWIKI
Line 49: Line 49:
===exit while loop===
===exit while loop===
  break
  break
===skip one in loop===
continue


==bash history timestamp==
==bash history timestamp==

Revision as of 10:16, 17 January 2020

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


exit while loop

break


skip one in loop

continue

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
 }