Bash Syntax

TBotNik · 03-28-2021, 06:09 PM

All,

Quick Q:

Have this code reading file listings from a source file:

Code:

i=0;
while read -r file; do
	nfil=${file:7}         # Eliminate 1st 7 chars "file://"
	if {grep -i '/etc/' <<< $nfil} then; continue; fi
	array[ $i ]="${nfil}"
	(( i++ ))
	echo "N=> $i F=> $nfil"
done < "${src_fil}"

The "grep" line is to eliminate any "/etc/" files from processing.

Always getting these 2 error lines but no HOWTO explains these errors:

Code:

script.sh: line 34: syntax error near unexpected token `fi'
script.sh: line 34: `      if grep -i '/etc/' <<< $nfil then; continue; fi'

So why does it think the "fi" which is mandatory, unexpected?

Do you know why or is it actually something else, which BASH lies about constantly?

Cheers!

TBNK

TBotNik · 03-28-2021, 06:18 PM

All,

OK Bash was lying, it was the ";" after the "continue" cmd that it was barfing about and now it is just barfing about the "done" line, but really thinking the error is in one of the 2 lines before "done"!

Cheers!

scasey · 03-28-2021, 06:32 PM

I’d use grep -vi instead. Wrap all the code in an if or while grep -vi .... Different styles for different folks.

And those aren’t “lies”, they are reports of syntax errors. All languages do that... not just bash. They won’t happen when the syntax is correct.

rknichols · 03-28-2021, 06:36 PM

Quote:

Originally Posted by TBotNik

Code:

i=0;
while read -r file; do
	nfil=${file:7}         # Eliminate 1st 7 chars "file://"
	if {grep -i '/etc/' <<< $nfil} then; continue; fi
	array[ $i ]="${nfil}"
	(( i++ ))
	echo "N=> $i F=> $nfil"
done < "${src_fil}"

The syntax error is in the use of curly braces. To be syntactically correct, this line would have to be

Code:

if { grep -i '/etc/' <<< $nfil; } then; continue; fi

The space after the first "{" is important. The space before the closing "}" is just for appearance.

But in reality, the curly braces are unnecessary.

Code:

if grep -iq '/etc/' <<< $nfil; then; continue; fi

Note that I have added the "-q" option to the grep command. I doubt that you want to see those lines displayed on the terminal.

allend · 03-28-2021, 07:56 PM

This can also be done using the bash =~ binary operator rather than grep.

Code:

shopt -s nocasematch
i=0;
while read -r file; do
  nfil=${file:7}         # Eliminate 1st 7 chars "file://"
  if ! [[ $nfil =~ .*/etc/.* ]]; then
    array[ $i ]="${nfil}"
    (( i++ ))
    echo "N=> $i F=> $nfil"
  fi
done < "${src_fil}"
shopt -u nocasematch

pan64 · 03-29-2021, 01:30 AM

Quote:

Originally Posted by TBotNik

All,

OK Bash was lying, it was the ";" after the "continue" cmd

No, again no. bash is not lying, just you use incorrect syntax again and was not understood.
As it was already suggested please use shellcheck:

Code:

Line 5:
        if {grep -i '/etc/' <<< $nfil} then; continue; fi
        ^-- SC1009: The mentioned syntax error was in this if expression.
           ^-- SC1073: Couldn't parse this brace group. Fix to allow more checks.
            ^-- SC1054: You need a space after the '{'.
                                     ^-- SC1083: This } is literal. Check expression (missing ;/\n?) or quote it.
                                       ^-- SC1010: Use semicolon or linefeed before 'then' (or quote to make it literal).
                                                       ^-- SC1056: Expected a '}'. If you have one, try a ; or \n in front of it.
                                                         ^-- SC1072: Unexpected keyword/token. Fix any mentioned problems and try again.

You have to know the language if you want to use it. Bash (and the computer in general) cannot lie, will just try understand the text file you wrote.
When you brake the rules [of the language] the computer will try the best (and guess), but obviously has no chance to know what was the initial wish.....

So again: if you think bash is lying you ought to check which rule did you ignore.

MadeInGermany · 03-29-2021, 01:46 PM

All of the following is correct

Code:

if { grep -i '/etc/' <<< "$nfil"; }; then continue; fi

Code:

if grep -i '/etc/' <<< "$nfil"; then continue; fi

Code:

grep -i '/etc/' <<< "$nfil" && continue

Code:

[[ $nfil =~ /[eE][tT][cC]/ ]] && continue

Code:

[[ $nfil == */[eE][tT][cC]/* ]] && continue