wh-loopc.sh

一本完整的描述Unix Shell 编程的工具书的所有范例

#!/bin/bash
# wh-loopc.sh: Count to 10 in a "while" loop.

LIMIT=10
a=1

while [ "$a" -le $LIMIT ]
do
  echo -n "$a "
  let "a+=1"
done           # No surprises, so far.

echo; echo

# +=================================================================+

# Now, repeat with C-like syntax.

((a = 1))      # a=1
# Double parentheses permit space when setting a variable, as in C.

while (( a <= LIMIT ))   # Double parentheses, and no "$" preceding variables.
do
  echo -n "$a "
  ((a += 1))   # let "a+=1"
  # Yes, indeed.
  # Double parentheses permit incrementing a variable with C-like syntax.
done

echo

# Now, C programmers can feel right at home in Bash.

exit 0