linux - Bash script: bad interpreter

Question

Question: I get this error message:

export: bad interpreter: No such file or directory

when I execute this bash script:

#!/bin/bash
MONO_PREFIX=/opt/mono-2.6
GNOME_PREFIX=/opt/gnome-2.6
export DYLD_LIBRARY_PATH=$MONO_PREFIX/lib:$DYLD_LIBRARY_PATH
export LD_LIBRARY_PATH=$MONO_PREFIX/lib:$LD_LIBRARY_PATH
export C_INCLUDE_PATH=$MONO_PREFIX/include:$GNOME_PREFIX/include
export ACLOCAL_PATH=$MONO_PREFIX/share/aclocal
export PKG_CONFIG_PATH=$MONO_PREFIX/lib/pkgconfig:$GNOME_PREFIX/lib/pkgconfig
PATH=$MONO_PREFIX/bin:$PATH
PS1="[mono-2.6] w @ "

But the bash path seems to be correct:

asshat@IS1300:~/sources/mono-2.6# which bash
/bin/bash

asshat@IS1300:~# cd sources/
asshat@IS1300:~/sources# cd mono-2.6/
asshat@IS1300:~/sources/mono-2.6# ./mono-2.6-environment
export: bad interpreter: No such file or directory
asshat@IS1300:~/sources/mono-2.6# ls
download  mono-2.4  mono-2.4-environment  mono-2.6  mono-2.6-environment
asshat@IS1300:~/sources/mono-2.6# cp mono-2.6-environment mono-2.6-environment.sh
asshat@IS1300:~/sources/mono-2.6# ./mono-2.6-environment.sh
export: bad interpreter: No such file or directory
asshat@IS1300:~/sources/mono-2.6# ls
download  mono-2.4-environment  mono-2.6-environment
mono-2.4  mono-2.6              mono-2.6-environment.sh
asshat@IS1300:~/sources/mono-2.6# bash mono-2.6-environment
asshat@IS1300:~/sources/mono-2.6#

What am I doing wrong? Or is this a Lucid Lynx bug?

I did chmod + x

Answer 1

The first line, #!/bin/bash, tells Linux where to find the interpreter. The script should also be executable with chmod +x script.sh, which it appears you did.

It is highly likely that you created this file with a windows editor, which will place a <cr><lf> at the end of each line. This is the standard under dos / windows. OS X will place a <cr> at the end of each line. However, under Unix / Linux, the standard is to just put a <lf> at the end of the line.

Linux is now looking for a file called /bin/bash<cr> to interpret the file, where <cr> is a carriage return character, which is a valid file character under Linux. Such a file doesn't exist. Hence the error.

Solution: Edit the file with an editor on Linux and get rid of the extra <cr>. One tool that usually works when the file is edited on Windows is dos2unix.