vimwiki/tech/Bash.wiki

= Bash =

The shell itself

== Common syntax ==

I tend to forget it sometimes lol

=== Brackets ===

Remember '\[' is a program unto itself. Here are some common flags

* -z 
 - empty string
* -n not 
 - empty string
* == aka -eq 
 - equal
* != aka -ne 
 - not equal
* -lt 
 - less than
* -gt 
 - greater than
* -ge 
 - greater than or equal
* !
 - not
* && 
 - and
* || 
 - or
* -e 
 - file exists
* -r 
 - is readable
* -h 
 - is symlink
* -d 
 - is directory
* -s 
 - has data in it
* -f 
 - is file
* -x 
 - is executable

=== Variables ===

{{{
var=55
echo $var
  }}}
  
=== While ===

{{{
while [ condition ]; do
    echo "Hello world"
done
  }}}

=== Arays ===

{{{
Fruits={'Apple','Banana','Orange'}

Fruits[0]="Apple"
echo ${Fruits[0]}

declare -A sounds
sounds[dog]="bark"
sounds[cow]="moo"
sounds[bird]="tweet"
sounds[wolf]="howl"

echo ${sounds[dog]} # Dog's sound
echo ${sounds[@]}   # All values
echo ${!sounds[@]}  # All keys
echo ${#sounds[@]}  # Number of elements
unset sounds[dog]   # Delete dog
  }}}

=== Math ===

{{{
$((a + 200)) #add 200 to a
  }}}
  
  
=== Strings ===

{{{
${FOO%suffix} #remove suffix from foo
${FOO#prefix} #remove prefix from foo
${FOO/from/to} #replace first instance of from with to
${FOO//from/to} #replace all instances of from with to
${#FOO} #length of foo
  }}}
  
== Common tasks ==

Rename push all .png files through convert

{{{
for file in *.png; do
    convert $file "${file%.png}.eps"
done
  }}}






  
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