Bash shell脚本 - 设置变量时出错

Question

I'm new at bash scripting. I tried the following:

filename01 = ''

if [ $# -eq 0 ]
        then
                filename01 = 'newList01.txt'
        else
                filename01 = $1
fi

I get the following error:

./smallScript02.sh: line 9: filename01: command not found
./smallScript02.sh: line 13: filename01: command not found

I imagine that I am not treating the variables correctly, but I don't know how. Also, I am trying to use grep to extract the second and third words from a text file. The file looks like:

1966 Bart Starr QB Green Bay Packers 
1967 Johnny Unitas QB Baltimore Colts 
1968 Earl Morrall QB Baltimore Colts 
1969 Roman Gabriel QB Los Angeles Rams 
1970 John Brodie QB San Francisco 49ers 
1971 Alan Page DT Minnesota Vikings 
1972 Larry Brown RB Washington Redskins 

Any help would be appreciated

Answer 1

When you assign variables in bash, there should be no spaces on either side of the = sign.

# good
filename0="newList01.txt"
# bad
filename0 = "newlist01.txt"

For your second problem, use awk not grep . The following will extract the second and third items from each line of a file whose name is stored in $filename0 :

< $filename0 awk '{print $2 $3}'

Answer 2

In bash (and other bourne-type shells), you can use a default value if a variable is empty or not set:

filename01=${1:-newList01.txt}

I'd recommend spending some time with the bash manual: http://www.gnu.org/software/bash/manual/bashref.html

Here's a way to extract the name:

while read first second third rest; do
    echo $second $third
done < "$filename01"