Cannot compile while loop in shell scripting

kiki2009 · 10-01-2012, 01:48 PM

Dear Expert,
I try to compile this shell script it give me error

Code:

#!/bin/bash
#set n to 1
n=1
#continue until $n equals 5
while[$n -le 5]
do
  echo "Welcome $n times."
  n=$(( n+1 ))  #increments $n
done

Here is the error shown on terminal

Code:

./while.sh: line 5: while[1 -le 5]: command not found
./while.sh: line 6: syntax error near unexpected token `do'
./while.sh: line 6: `do'

rknichols · 10-01-2012, 01:58 PM

The '[' character is a command, not a builtin part of the "while" syntax. Both the '[' and ']' characters need to be delimited by white space:

Code:

while [ $n -le 5 ]
do
.
.
.
done

grail · 10-01-2012, 02:16 PM

Also, as you are using bash I would recommend using [[ over [ (see here for more info) and (( over [[ when performing
arithmetic expressions (see here)

kiki2009 · 10-02-2012, 08:14 AM

Thank alots for that information. Its helps me to learn since i'm new to linux.