function string manipulation returns different data than direct usage

Question

Having already learned much here, I'm back with a perplexing problem. I can run some string manipulation commands directly and get the expected results. When I put them in a function, the results are wonky.

Am I having brain cramp and missing the obvious? My code, with tests:

    get_name() { 
    # single-purpose function to build student name from FL
    # takes first word of string (first name) and moves to end
    # last name could be one or two words; 
    # first names including space will be mistreated, but for now, is best solution
    local string=$1 namefirst namelast name
    namefirst=${string%% *} # returns text up to specified char (" ")
    namelast=${string#$namefirst } # returns text minus specified string at start
    name=$namelast"_"$namefirst
    echo ${name// /_}
}


student="First Last1 Last2, Grade 1"
studentname=${student%%,*} # returns text up to specified char (,)
string=$studentname # save for standalone test

studentname=$(get_name $studentname)
echo "function studentname = $studentname"

echo "Now run same manips outside of function:"
namefirst=${string%% *} # returns text up to specified char (" ")
echo $namefirst
namelast=${string#$namefirst } # returns text minus specified string at start
echo $namelast
name=$namelast"_"$namefirst
echo ${name// /_}

The results:

function studentname = First_First
Now run same manips outside of function:
First
Last1 Last2
Last1_Last2_First

The last three lines show the expected string results. Why would the function's namelast fail (is set to namefirst)?

Many thanks for any input.

namelast=${string#$namefirst } .. Whatever is after the sign # is read as a comment.. You will have to put it differently to get the desired result — LogicIO
– LogicIO, Commented Feb 8, 2015 at 6:20
If this were the case, Vineeth, the tests as run after the function call would have returned the same result. In fact, # in string manipulation serves a special function. See e.g. the very useful tldp.org/LDP/abs/html/string-manipulation.html . — Abe Hendin
– Abe Hendin, Commented Feb 8, 2015 at 6:34

anubhava · Accepted Answer · 2015-02-08 06:22:28Z

1

Problem is unquoted string here:

get_name $studentname

Since $studentname variable has value: First Last1 Last2

That has spaces in it therefore sending it without quotes is sending only the first word before space i.e. calling it as:

get_name "First"

Your function call should be:

get_name "$studentname"

answered Feb 8, 2015 at 6:22

anubhava

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1 Comment

Abe Hendin Over a year ago

Geez. Total brain cramp. Somehow the one thing I didn't check was the first string coming into the function. Thanks, anubhava.

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