I got this error while running my script with nohup sh:

 syntax error near unexpected token `('

My script is as follow:

grep -A 3 'successful\|ERROR COUNT EXCEEDED' *.log  > ${report_log};
echo ${report_log};
if grep "ERROR COUNT EXCEEDED" ${report_log}; then
RESULT_MSG="Execution successful";
if grep '\([1-9]\d*\b\)' ${report_log} | grep 'data errors'; then
   RESULT_MSG="Execution with ERROR";
cat ${report_log} <(echo "-----------") <(echo "${MAX_ERR_COUNT_EXCEED_MSG}") <(echo "${RESULT_MSG}") | mailx -s "Test Result" [email protected]

It is a script to filter through some log files and generate a reporting email on the execution status from those files.

The error seems to come from the usage of <( in the script, but having added the bash shebang i thought it should work. The script run without issue if running using the command below:

. ./script.sh

Any help or advice is appreciated. Thanks.

  • What do you mean by "running my script with nohup sh"? Do you start it as nohup sh /path/to/your/script.sh or as nohup /path/to/your/script.sh? In the first case the shebang line is ignored because the interpreter is called explicitly. Jan 29, 2015 at 9:09
  • Hi, i'm running it using nohup sh /path/to/script. In that case is there anyway i can overwrite the interpreter? This is because this script is called by another script and generally others run those scripts using nohup sh
    – ipohfly
    Jan 29, 2015 at 9:13
  • when i try running it via nohup /path/to/script i get an error nohup: cannot run command 'script.sh': No such file or directory instead
    – ipohfly
    Jan 29, 2015 at 9:17
  • So you cannot influence how the script is called. Can you modify the script? Jan 29, 2015 at 9:17
  • have you tried nohup bash /path/to/myscript.sh ?
    – Archemar
    Jan 29, 2015 at 9:19

1 Answer 1


The problem is that running the script as nohup sh /path/to/your/script.sh overrides the shebang line interpreter. When called as sh then bash turns off certain features (that is probably similar with other shells) and thus cannot parse process substitution any more.

The solution is to make sure that bash is running without restrictions. This can be done by checking for an environment variable and call the script again with bash (instead of sh):

#! /bin/bash

if [ "YES" = "$RUNNING_AS_BASH" ]; then
        eval 'cat <(echo "-----------")'
        test -f "$0" || exit 1
        RUNNING_AS_BASH="YES" exec bash "$0"

Unfortunately bash as sh parses the whole if structure. Thus in order to avoid the error the incompatible syntax must be hidden in an eval statement.

This can be avoided if the eval action is taken out of the if structure because the rest of the script is not parsed:

#! /bin/bash

if [ "YES" != "$RUNNING_AS_BASH" ]; then
        test -f "$0" || exit 1
        RUNNING_AS_BASH="YES" exec bash "$0"

cat <(echo "-----------")

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