#!/bin/bash
jobname="job_201312161447_0003"
jobname_pre=${jobname:0:16}
jobname_post=${jobname:17}
This bash script gives me Bad substitution error on ubuntu. Any help will be highly appreciated.
The default shell (/bin/sh
) under Ubuntu points to dash
, not bash
.
me@pc:~$ readlink -f $(which sh)
/bin/dash
So if you chmod +x your_script_file.sh
and then run it with ./your_script_file.sh
, or if you run it with bash your_script_file.sh
, it should work fine.
Running it with sh your_script_file.sh
will not work because the hashbang line will be ignored and the script will be interpreted by dash
, which does not support that string substitution syntax.
Your script syntax is valid bash and good.
Possible causes for the failure:
Your bash
is not really bash but ksh
or some other shell which doesn't understand bash's parameter substitution. Because your script looks fine and works with bash.
Do ls -l /bin/bash
and check it's really bash and not sym-linked to some other shell.
If you do have bash on your system, then you may be executing your script the wrong way like: ksh script.sh
or sh script.sh
(and your default shell is not bash). Since you have proper shebang, if you have bash ./script.sh
or bash ./script.sh
should be fine.
Not relevant to your example, but you can also get the Bad substitution
error in Bash for any substitution syntax that Bash does not recognize. This could be:
bash -c '${x }'
bash -c '${x;-}'
bash -c '${x@Q}'
before Bash 4.4.If you have multiple substitutions in the same expression, Bash may not be very helpful in pinpointing the problematic expression. E.g.:
$ bash -c '"${x } multiline string
$y"'
bash: line 1: ${x } multiline string
$y: bad substitution
Looks like "+x" causes problems:
root@raspi1:~# cat > /tmp/btest
#!/bin/bash
jobname="job_201312161447_0003"
jobname_pre=${jobname:0:16}
jobname_post=${jobname:17}
root@raspi1:~# chmod +x /tmp/btest
root@raspi1:~# /tmp/btest
root@raspi1:~# sh -x /tmp/btest
+ jobname=job_201312161447_0003
/tmp/btest: 4: /tmp/btest: Bad substitution
in my case (under ubuntu 18.04), I have mixed $( ${} )
that works fine:
BACKUPED_NB=$(ls ${HOST_BACKUP_DIR}*${CONTAINER_NAME}.backup.sql.gz | wc --lines)
full example here.
cut
?cut -d_ -f1,2 <<< "$jobname"
andcut -d_ -f3 <<< "$jobname"
make it – fedorqui 'SO stop harming'sh script.sh
it gets a "Bad substitution" error. – fedorqui 'SO stop harming'