Awk syntax error when command is executed through a shell script however the command works fine when executed from Linux bash shell

Question

I am running this command

awk '{print "Removing " ORS $0;system("rm " $0 ORS  " if [ $? -eq 0 ]" ORS "then" ORS "echo file  " $0 " has been removed." ORS "fi")}' <(cat /tmp/findo)

On bash and the command works however when executed from a shell script it throws the underlying error

Here is the example and you may look at the 'line 23 error'

# sh -x rvarlog_util.sh
+ findout=/tmp/findout
+ '[' -e /tmp/findout ']'
++ du -sm /var/log
++ awk '{print $1+0}'
+ cdu=2372
++ awk '{print $1+0}'
++ grep total
++ du -m --max-depth=1 -c -m -x /var/log/messages /var/log/messages-20190310 /var/log/messages-20190323-1553338190.gz /var/log/messages-20190324-1553424406.gz /var/log/messages-20190324-1553456095.gz /var/log/messages-20190324-1553456293.gz /var/log/messages-20190324-1553457237.gz /var/log/messages-20190324-1553457268.gz /var/log/maillog-20190324-1553456095.gz /var/log/boot.log /var/log/audit/audit.log /var/log/audit/audit.log-20190311-1552325090.gz /var/log/puppetlabs
+ fusage=2258
rvarlog_util.sh: line 23: syntax error near unexpected token `('
rvarlog_util.sh: line 23: `awk '{print "Removing " ORS $0;system("rm " $0 ORS  " if [ $? -eq 0 ]" ORS "then" ORS "echo file  " $0 " has been removed." ORS "fi")}' <(cat /tmp/findo)'

awk '{print "Removing " ORS $0;system("rm " $0 ORS " if [ $? -eq 0 ]" ORS "then" ORS "echo file " $0 " has been removed." ORS "fi")}' <(cat /tmp/findout) is the command. Are you saying I should be formatting line 23 specifically? — rony thomas
– rony thomas, Commented Mar 25, 2019 at 12:16
See the link in my comment above for details of how to make your code above display correctly. — Paul R
– Paul R, Commented Mar 25, 2019 at 12:23
The problem is almost certainly on some earlier line of your shell script that you aren't showing us, e.g. a missing quote. Post a minimal reproducible example shell script that reproduces the error. Using shell to call awk to call system to call shell to call rm is a terrible idea btw - just call rm directly from shell. — Ed Morton
– Ed Morton, Commented Mar 25, 2019 at 12:38

Gordon Davisson · Accepted Answer · 2019-03-26 01:03:57Z

3

@Ibraheem has the right solution, but so far nobody's spotted the problem. It's that you're using a process substitution (<(cat /tmp/findo)), but running the script with sh rather than bash. Process substitution isn't available in all shells (or even bash when it's invoked as "sh").

There are a couple of ways to fix this, and I'd recommend doing both ('cause they're good ideas on their own):

Don't use <(cat somefile), use a plain redirect, like <somefile. The process-substituted cat command is an overly complex, fragile, and inefficient way to read from a file.
Give the script a proper shebang line (#!/bin/bash or #!/usr/bin/env bash), make it executable (chmod +x rvarlog_util.sh), and run it directly by entering its path (./rvarlog_util.sh) rather than explicitly specifying a shell (sh or bash). In general, the script should "know" which shell it's written for, and overriding that (by explicitly specifying a shell when you run it) is a bad idea.

edited Mar 26, 2019 at 1:03

answered Mar 25, 2019 at 18:21

Gordon Davisson

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2 Comments

Shawn Over a year ago

Quite a few shells support <(command), actually, not just bash. (dash, used for /bin/sh on Debian, Ubuntu, and many other linux distributions isn't one of them, though.)

Gordon Davisson Over a year ago

@Shawn Wow, I had no idea, but at least zsh and ksh 93 both support process substitution. I'll edit my answer to correct this.

Ibraheem · Accepted Answer · 2019-03-25 18:19:47Z

2

from your awk command, what I understood that you are trying to remove files who's names found in /tmp/findo file, is that correct? then replace your awk command with below code and see if it works, BUT make sure that the file names in /tmp/findo contain absolute path to the required files you are trying to remove

while read -r files
do
  rm "$files" 
  if [ $? -eq 0 ] 
  then
     "echo $files has been removed."
  fi
done < /tmp/findo

edited Mar 25, 2019 at 18:19

answered Mar 25, 2019 at 17:54

Ibraheem

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4 Comments

Gordon Davisson Over a year ago

I'd recommend double-quoting $files both times it's used (and for the echo command, double-quote the entire string). Also, you can simplify it by testing the result of rm directly: if rm "$files".

Wiimm Over a year ago

Or simpler: xargs -d'\n' rm -v </tmp/findo

rony thomas Over a year ago

@Wiimm this one liner does the job, thank you very much

Ibraheem Over a year ago

@ronythomas welcome, you can accept the answer if that is all you needed,

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