Bash makes it extremely easy to define functions with parameters. In this example, we will create the hello_world function and pass a string as an argument by its position using shell variables. That is $1 , $2 , and so forth. Copy #!/bin/bash hello_world () { echo "Hello $1" } hello_world "World Again!"
$1 means an input argument and -z means non-defined or empty. You're testing whether an input argument to the script was defined when running the script. Follow this answer to receive notifications.
bash [filename] runs the commands saved in a file. $@ refers to all of a shell script's command-line arguments. $1 , $2 , etc., refer to the first command-line argument, the second command-line argument, etc. Place variables in quotes if the values might have spaces in them.
There is no difference if you do not put $* or $@ in quotes. But if you put them inside quotes (which you should, as a general good practice), then $@ will pass your parameters as separate parameters, whereas $* will just pass all params as a single parameter.
You should add quotes and also, your function declaration is wrong.
myFunction()
{
echo "$1"
echo "$2"
echo "$3"
}
And like the others, it works for me as well.
Another solution to the issue above is to set each string to a variable, call the function with variables denoted by a literal dollar sign \$
. Then in the function use eval
to read the variable and output as expected.
#!/usr/bin/ksh
myFunction()
{
eval string1="$1"
eval string2="$2"
eval string3="$3"
echo "string1 = ${string1}"
echo "string2 = ${string2}"
echo "string3 = ${string3}"
}
var1="firstString"
var2="second string with spaces"
var3="thirdString"
myFunction "\${var1}" "\${var2}" "\${var3}"
exit 0
Output is then:
string1 = firstString
string2 = second string with spaces
string3 = thirdString
In trying to solve a similar problem to this, I was running into the issue of UNIX thinking my variables were space delimeted. I was trying to pass a pipe delimited string to a function using awk
to set a series of variables later used to create a report. I initially tried the solution posted by ghostdog74 but could not get it to work as not all of my parameters were being passed in quotes. After adding double-quotes to each parameter it then began to function as expected.
Below is the before state of my code and fully functioning after state.
Before - Non Functioning Code
#!/usr/bin/ksh
#*******************************************************************************
# Setup Function To Extract Each Field For The Error Report
#*******************************************************************************
getField(){
detailedString="$1"
fieldNumber=$2
# Retrieves Column ${fieldNumber} From The Pipe Delimited ${detailedString}
# And Strips Leading And Trailing Spaces
echo ${detailedString} | awk -F '|' -v VAR=${fieldNumber} '{ print $VAR }' | sed 's/^[ \t]*//;s/[ \t]*$//'
}
while read LINE
do
var1="$LINE"
# Below Does Not Work Since There Are Not Quotes Around The 3
iputId=$(getField "${var1}" 3)
done<${someFile}
exit 0
After - Functioning Code
#!/usr/bin/ksh
#*******************************************************************************
# Setup Function To Extract Each Field For The Report
#*******************************************************************************
getField(){
detailedString="$1"
fieldNumber=$2
# Retrieves Column ${fieldNumber} From The Pipe Delimited ${detailedString}
# And Strips Leading And Trailing Spaces
echo ${detailedString} | awk -F '|' -v VAR=${fieldNumber} '{ print $VAR }' | sed 's/^[ \t]*//;s/[ \t]*$//'
}
while read LINE
do
var1="$LINE"
# Below Now Works As There Are Quotes Around The 3
iputId=$(getField "${var1}" "3")
done<${someFile}
exit 0
A more dynamic way would be:
function myFunction {
for i in "$*"; do echo "$i"; done;
}
The simplest solution to this problem is that you just need to use \"
for space separated arguments when running a shell script:
#!/bin/bash
myFunction() {
echo $1
echo $2
echo $3
}
myFunction "firstString" "\"Hello World\"" "thirdString"
Your definition of myFunction is wrong. It should be:
myFunction()
{
# same as before
}
or:
function myFunction
{
# same as before
}
Anyway, it looks fine and works fine for me on Bash 3.2.48.
Simple solution that worked for me -- quoted $@
Test(){
set -x
grep "$@" /etc/hosts
set +x
}
Test -i "3 rb"
+ grep -i '3 rb' /etc/hosts
I could verify the actual grep command (thanks to set -x).
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