[Solved-4 Solutions] Test-line 4-2- command not found
Error Description:
- When we try the following code:
#!/bin/bash
echo Script name: $0
echo $# arguments
if [$# -ne 1];
then echo "illegal number of parameters"
fi
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- We get the following error:
Test-line 4-2- command not found
Solution 1:
- Just like any other simple command, [ ... ] or test requires spaces between its arguments.
if [ "$#" -ne 1 ]; then
echo "Illegal number of parameters"
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- Or
if test "$#" -ne 1; then
echo "Illegal number of parameters"
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- When in Bash, prefer using [[ ]] instead as it doesn't do word splitting and pathname expansion to its variables that quoting may not be necessary unless it's part of an expression.
[[ $# -ne 1 ]]
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- It also has some other features like unquoted condition grouping, pattern matching (extended pattern matching with extglob) and regex matching.
- The following example checks if arguments are valid. It allows a single argument or two.
[[ ($# -eq 1 || ($# -eq 2 && $2 == <glob pattern>)) && $1 =~ <regex pattern> ]]
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- For pure arithmetic expressions, using (( )) to some may still be better, but they are still possible in [[ ]] with its arithmetic operators like -eq, -ne, -lt, -le, -gt, or -ge by placing the expression as a single string argument:
A=1
[[ 'A + 1' -eq 2 ]] && echo true ## Prints true.
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- That should be helpful if you would need to combine it with other features of [[ ]] as well.
Solution 2:
- It might be a good idea to use arithmetic expressions if you're dealing with numbers.
if (( $# != 1 )); then
echo "Illegal number of parameters"
fi
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Solution 3:
- A simple one liner that works can be done using:
[ "$#" -ne 1 ] && ( usage && exit 1 ) || main
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- This breaks down to:
- test the bash variable for size of parameters $# not equals 1 (our number of sub commands)
- if true then call usage() function and exit with status 1
- else call main() function
- Thinks to note:
- usage() can just be simple echo "$0: params"
- main can be one long script
Solution 4:
- If you're only interested in bailing if a particular argument is missing, Parameter Substitution is great:
#!/bin/bash
# usage-message.sh
: ${1?"Usage: $0 ARGUMENT"}
# Script exits here if command-line parameter absent,
#+ with following error message.
# usage-message.sh: 1: Usage: usage-message.sh ARGUMENT