echo - 语法错误：错误的替换

Question

A script with a problem:

  1 #!/bin/bash
  2
  3 skl="test"
  4 # get length
  5 leng=$(expr length $skl)
  6 # get desired length
  7 leng=$(expr 22 - $leng)
  8
  9 # get desired string
 10 str=$(printf "%${leng}s" "-")
 11
 12 # replace empty spaces
 13 str=$(echo "${str// /-}")
 14
 15 # output
 16 echo "$str  obd: $skl  $str"
 17

but it outputs:

name.sh: 13: Syntax error: Bad substitution

please help, thanks I would be very grateful :)

Answer 1

The following line:

str=$(echo "${str// /-}")

is resulting into Syntax error: Bad substitution because you are not executing your script using bash . You are either executing your script using sh or dash which is causing the error.

---

EDIT: In order to fix your script to enable it to work with sh and dash in addition to bash , you could replace the following lines:

# get desired string
str=$(printf "%${leng}s" "-")

# replace empty spaces
str=$(echo "${str// /-}")

with

str=$(printf '=%.0s' $(seq $leng) | tr '=' '-')

Answer 2

Take out all unnecessary expr calls, using pure BASH features:

#!/bin/bash

skl="test"
# get length
leng=${#skl}
# get desired length
leng=$((22 - leng))

# get desired string
str=$(printf "%${leng}s" "-")

# replace empty spaces
str=$(echo "${str// /-}")

# output
echo "$str  obd: $skl  $str"