====== Bash Functions ======
==== index # Print the position of $2 in $1 ====
<code bash>
index() #@ Print the position of $2 in $1
{ #@ USAGE: index STRING SUBSTRING
local idx
case $1 in
*$2*) idx=${1%%$2*}
echo $(( ${#idx} + 1 )) ;;
*) echo 0 ;;
esac
}
</code>
[[http://www.linkedin.com/groups/Fridays-function-index-3716796.S.237745984?view=&srchtype=discussedNews&gid=3716796&item=237745984&type=member&trk=eml-anet_dig-b_pd-ttl-cn&ut=0kcr73WwfdW5I1 | From Article]]

==== die # Exit with error code and optional message ====
<code bash>
die() #@ Exit with error code and optional message
{ #@ USAGE: die RETURN_CODE [MESSAGE]
result=$1
shift
[ -n "$*" ] && printf "%s\n" "$*" >&2
exit "$result"
}
</code>
[[ http://www.linkedin.com/groups/Fridays-function-die-3716796.S.236067929?qid=da8e8fcc-4fda-480a-91a1-3ef360d90e53&trk=group_most_popular_guest-0-b-ttl&goback=.gde_3716796_member_237745984.gmp_3716796 | From Article ]]


==== Place SUBSTRING over STRING beginning at OFFSET  ====
<code bash>
overlay() #@ Place SUBSTRING over STRING beginning at OFFSET 
{ #@ USAGE: overlay VARNAME SUBSTRING OFFSET 
local varname=$1 substr=$2 start=$3 string 
eval "string=\${$varname}" 
left=${string:0:start} 
right=${string:start+${#substr}} 
printf -v "$varname" %s%s%s "$left" "$substr" "$right" 
}
</code>
[[ http://www.linkedin.com/groups/Fridays-function-overlay-3716796.S.241936021?view=&gid=3716796&type=member&item=241936021&trk=eml-anet_dig-b_nd-pst_ttle-cn | From Article ]]

==== Print the ASCII value of the first character ====
<code bash>
asc() #@ Print the ASCII value of the first character of each argument 
{ #@ USAGE: asc STRING ... 
for char 
do 
printf "%d${EOV-\n}" "'$char" 
done
}
</code>
[[ http://www.linkedin.com/groups/Fridays-function-asc-Print-ASCII-3716796.S.252009597?view=&gid=3716796&type=member&item=252009597&trk=eml-anet_dig-b_nd-pst_ttle-cn | From Article ]]

==== Print argument in reverse ====
<code bash>
revword() #@ print each argument with bytes reversed
for w
do
len=${#w}
w2=
n=0
while (( ${#w2} < len ))
do
w2=${w:n++:1}$w2
done
printf "%s\n" "$w2"
done
</code>
[[ http://www.linkedin.com/groups/Fridays-function-revword-3716796.S.253755071?view=&gid=3716796&type=member&item=253755071&trk=eml-anet_dig-b_nd-pst_ttle-cn | From Article ]]

==== Add directory or directories to PATH ====
<code bash>
addpath() #@ add directory or directories to $PATH
{ #@ USAGE: addpath DIR ...
local prefix=0 quiet=0 OPTIND=1 p

while getopts iq var
do
case "$var" in
i) prefix=1 ;;
q) quiet=1 ;;
esac
done
shift $(( $OPTIND - 1 ))

for p
do
p=${p%"${p##*[!/]}"} ## remove trailing slashes
case $p in
""|.) continue ;;
esac
case :$PATH: in
*:$p:*)
(( quiet == 0 )) && echo "addpath: $p already in path" >&2
continue
;;
esac
if [ -d "$p" ]
then
(( prefix == 1 )) && PATH=$p:$PATH || PATH=$PATH:$p
else
[ $quiet -eq 0 ] && echo "addpath: $p is not a directory" >&2
fi
done
export PATH ## probably unnecessary
}
</code>

[[ http://www.linkedin.com/groups/Fridays-function-addpath-Add-one-3716796.S.255801510 | From Article ]]

==== Return random date in given range of years ====
<code bash>
random_date() #@ Return random date in given range of years
{ #@ USAGE: random_date FIRST LAST [VAR]
#@ Global variables set: random_date [VAR]
local first=${1:-1752} last=${2:-2100} var=$3
declare -i year month day dim
year=$(( RANDOM % (last-first) + first ))
month=$(( RANDOM % 12 + 1 ))
days_in_month dim "$month" "$year"
day=$(( RANDOM % dim + 1 ))
printf -v random_date "%d-%02d-%02d" "$year" "$month" "$day"
is_var "$var" &&
printf -v "$var" %s "$random_date" ||
printf "%s\n" "$random_date"
}
</code>

[[ http://www.linkedin.com/groups/Fridays-function-randomdate-Return-random-3716796.S.5799573907065286656 | From Article ]]

==== Check if it is factor ====
<code bash>
is_factor() #@ Return successfully if $2 is a factor of $1
{ #@ USAGE: is_factor NUMBER FACTOR
local number=$1 factor=$2
(( ((number / factor) * factor) == number ))
}
</code>

[[ http://www.linkedin.com/groups/Fridays-function-isfactor-Return-successfully-3716796.S.5794561860833390593 | From Article ]]

==== Check if it is factor ====
<code bash>
dec2bin() #@ Convert decimal integer to binary optionally padding with zeroes 
{ #@ USAGE: dec2bin INT [WIDTH] [VAR] 
local val=$1 _w=$2 var=$3 _b=2 _r bin 
if (( $# == 1 )) || is_var "$2" ## is_var() posted last month 
then 
_w=1 
fi 
while ((val)) 
do 
_r=$(( $val % $_b )) 
bin=$_r$bin; 
val=$(( val / _b )) 
done 
printf -v bin "%0${_w}d" "$((10#$bin))" 
is_var "$var" && printf -v "$var" %s "$bin" || printf "%s\n" "$bin" 
}
</code>

[[ http://www.linkedin.com/groups/Fridays-functon-dec2bin-Convert-decimal-3716796.S.277082108 | From Article ]]

==== List running process matching args ====
<code bash>
psg() #@ Show all running processes matching ARG[s]
{ #@ USAGE: psg STRING ...
local ss
for ss
do
## Enclose first character in brackets so grep doesn't show its own process
ss=\[${ss:0:1}\]${ss#?}
ps -ef | grep "$ss"
[ $# -gt 1 ] && echo
done
}
</code>

[[ http://www.linkedin.com/groups/Fridays-function-psg-Show-all-3716796.S.5827514953933824001?view=&gid=3716796&type=member&item=5827514953933824001&trk=eml-anet_dig-b_nd-pst_ttle-cn | From Article ]]

==== Print the result of arithmetical calulation ====

<code bash>
calc() #@ Print the result of arithmetical calulation
{ #@ USAGE: calc EXPRESSION
awk 'BEGIN {print '"${*//x/*}"'}'
}
</code>

[[ http://www.linkedin.com/groups/Fridays-function-calc-Print-result-3716796.S.5832542139925430274?view=&srchtype=discussedNews&gid=3716796&item=5832542139925430274&type=member&trk=eml-anet_dig-b_pd-ttl-cn&fromEmail=&ut=04XvycE_RsJm41 | From Article ]]

==== Print lines on screen descending from the current point ====

<code bash>
lines() #@ Print lines on screen descending from the current point
{ #@ USAGE: [printat ROW COL [STRING];] lines STRING ...
local cu_save=$'\e[s' cu_restore=$'\e[u' cu_down=$'\e[B'
printf "$cu_restore$cu_down$cu_save%s" "$@"
}
</code>

[[ https://www.linkedin.com/groups/Fridays-function-lines-Print-lines-3716796.S.5900869707560415236?view=&item=5900869707560415236&type=member&gid=3716796&trk=eml-b2_anet_digest-hero-1-hero-disc-disc-0&midToken=AQG8JYIVdmXjvA&fromEmail=fromEmail&ut=0fjZG80YW_UCk1 | From Article ]]

==== Integer or Decimal ====

<code bash>
case ${1#-} in 
*[!0-9.]*|.) echo not an integer or float ;; 
*.*) echo float ;; 
*) echo int ;; 
esac
</code>
- OR - 
<code bash>
i=$1 
let 'i++' 

if [ $? -eq 0 ] # check in not error returned 
then 
echo "integer" 
else 
echo "not integer" 
fi
</code>

[[ https://www.linkedin.com/groups/How-can-i-verify-if-3716796.S.5862974732210556931?view=&item=5862974732210556931&type=member&gid=3716796&trk=eml-b2_anet_digest-null-2-null&fromEmail=fromEmail&ut=3KLlfwU1D4UCk1 | From Article ]]

==== floating point multiplication ====
<code bash>
fpmul() #@ Perform floating-point multiplication in the shell
{ #@ USAGE: fpmul [VAR] NUM.DEC ...
local _var= _places _tot _neg _n _int _dec _df _fpmul
if [[ ${1^^} =~ ^[A-Z_][A-Z0-9_]*$ ]]
then
_var=$1
shift
fi
_places=
_tot=1
_neg=
for _n
do
## 2 negatives make a positive
case $_n in
-*) [ "$_neg" = '-' ] && _neg= || _neg='-'
_n=${_n#-}
;;
esac

## Check for non-numeric characters
case $_n in
*[!0-9.]*) return 1 ;;
esac

## count the number of decimal _places,
## then remove the decimal point
case $_n in
.*) _int=
_dec=${_n#?}
_places=$_places$_dec
_n=$_dec
;;
*.*) _dec=${_n#*.}
_int=${_n%.*}
_places=$_places$_dec
_n=$_int$_dec
;;
esac

## remove leading zeroes
while :
do
case $_n in
""|0) _n=0
_fpmul=0
return
;;
0*) _n=${_n#0} ;;
*) break;;
esac
done

## multiply by the previous _total
_tot=$(( $_tot * ${_n:-0} ))

## report any overflow error
case $_tot in
-*) printf "fpmul: overflow error: %s\n" "$_tot" >&2
return 1
;;
esac
done

while [ ${#_tot} -lt ${#_places} ]
do
_tot=0$_tot
done

_df=
while [ ${#_df} -lt ${#_places} ]
do
left=${_tot%?}
_df=${_tot#$left}$_df
_tot=$left
done
_fpmul=$_tot${_df:+.$_df}

## remove trailing zeroes or decimal points
while :
do
case $_fpmul in
*.*[0\ ]|*.) _fpmul=${_fpmul%?} ;;
.*) _fpmul=0$_fpmul ;;
*) break ;;
esac
done

[[ $_var ]] &&
printf -v "$_var" %s "$_fpmul" ||
printf '%s\n' "$_fpmul"
}
num.dec
</code>

[[http://www.linkedin.com/groups/Fridays-function-fpmul-Perform-floatingpoint-3716796.S.5921339472191987716?view=&item=5921339472191987716&type=member&gid=3716796&trk=eml-b2_anet_digest-hero-1-hero-disc-disc-0&midToken=AQG8JYIVdmXjvA&fromEmail=fromEmail&ut=3_RJ7vAOch56s1|From article]]

==== show array ====
<code bash>
ashow() #@ Display contents of array[s]
{ #@ USAGE: ashow ARRAYNAME ...
local _arg _num=0
for arg
do
:; ((_num++)) && echo
:; declare -n array=$arg
:; [[ -n ${array[*]} ]] && printf '%s\n' "${array[@]}"
done
}
</code>

[[https://www.linkedin.com/groups/Fridays-function-ashow-Display-contents-3716796.S.5918816399794409474?view=&item=5918816399794409474&type=member&gid=3716796&trk=eml-b2_anet_digest-hero-4-hero-disc-disc-0&midToken=AQG8JYIVdmXjvA&fromEmail=fromEmail&ut=19mP4Lva0K56s1|From Article]]

==== Reverse Word ====
<code bash>
revword() #@ Reverse the order of characters in STRING
{ #@ USAGE: revword STRING [VAR]
local _n _word=$1 _var=$2 _len _r _rw= _l
while read -n1 _l
do
_rw=$_l$_rw
done <<< "$_word"
[[ ${_var^^} =~ ^[A-Z_][A-Z0-9_]*$ ]] &&
printf -v "$_var" %s "$_rw" ||
printf '%s\n' "$_rw"
}
</code>

[[ https://www.linkedin.com/groups/Fridays-function-revword-Reverse-order-3716796.S.5916260779903975428?view=&item=5916260779903975428&type=member&gid=3716796&trk=eml-b2_anet_digest-hero-1-hero-disc-disc-0&midToken=AQG8JYIVdmXjvA&fromEmail=fromEmail&ut=13sqjyjg1356s1 | From Article ]]

==== Trim Spaces ====
<code bash>
trim() #@ Trim spaces (or char in $2) from both ends of $1
{ #@ USAGE: trim STRING [CHAR [VAR]]
local _trim_string _trim=$1 _char=${2:- } _var=$3
_trim_string=${_trim##*[!$_char]}
_trim=${_trim%"$_trim_string"}
_trim_string=${_trim%%[!$_char]*}
_trim=${_trim#"$_trim_string"}
is_var "$_var" &&
printf -v "$_var" %s "$_trim" ||
printf '%s\n' "$_trim"
}
</code>

[[ https://www.linkedin.com/groups/Fridays-function-trim-Trim-spaces-3716796.S.5908643378429460481?view=&item=5908643378429460481&type=member&gid=3716796&trk=eml-b2_anet_digest-hero-1-hero-disc-disc-0&midToken=AQG8JYIVdmXjvA&fromEmail=fromEmail&ut=2lgJiLIHdb56s1 | From Article ]]