I bumped into the following problem: I'm writing a Linux bash script which does the following:
\ncharacter from the end of the line just read
ls ls -l ls -ltra ps as
The execution of the bash file should get the first line, and execute it, but while the
\n present, the shell just outputs "command not found: ls"
That part of the script looks like this
read line if [ -n "$line" ]; then #if not empty line #myline=`echo -n $line | tr -d '\n'` #myline=`echo -e $line | sed ':start /^.*$/N;s/\n//g; t start'` myline=`echo -n $line | tr -d "\n"` $myline #execute it cat $fname | tail -n+2 > $fname.txt mv $fname.txt $fname fi
Commented you have the things I tried before asking SO. Any solutions? I'm smashing my brains for the last couple of hours over this...
I always like
perl -ne 'chomp and print' , for trimming newlines. Nice and easy to remember.
ls -l | perl -ne 'chomp and print'
I don't think that is your problem here though. Although I'm not sure I understand how you're passing the commands in the file through to the 'read' in your shell script.
With a test script of my own like this (test.sh)
read line if [ -n "$line" ]; then $line fi
and a sample input file like this (test.cmds)
ls ls -l ls -ltra
If I run it like this
./test.sh < test.cmds, I see the expected result, which is to run the first command 'ls' on the current working directory.
Perhaps your input file has additional non-printable characters in it ?
mine looks like this
od -c test.cmds 0000000 l s \n l s - l \n l s - l t 0000020 r a \n 0000023
From your comments below, I suspect you may have carriage returns ( "\r" ) in your input file, which is not the same thing as a newline. Is the input file originally in DOS format ? If so, then you need to convert the 2 byte DOS line ending "\r\n" to the single byte UNIX one, "\n" to achieve the expected results.
You should be able to do this by swapping the "\n" for "\r" in any of your commented out lines.
Someone already wrote a program which executes shell commands: sh file
If you really only want to execute the first line of a file:
head -n 1 file |sh
If your problem is carriage-returns:
tr -d '\r' <file |sh