Bash Space-Separated (e.g., --option argument)
cat >/tmp/demo-space-separated.sh <<'EOF'
#!/bin/bash
POSITIONAL=()
while [[ $# -gt 0 ]]; do
key="$1"
case $key in
-e|--extension)
EXTENSION="$2"
shift # past argument
shift # past value
;;
-s|--searchpath)
SEARCHPATH="$2"
shift # past argument
shift # past value
;;
-l|--lib)
LIBPATH="$2"
shift # past argument
shift # past value
;;
--default)
DEFAULT=YES
shift # past argument
;;
*) # unknown option
POSITIONAL+=("$1") # save it in an array for later
shift # past argument
;;
esac
done
set -- "${POSITIONAL[@]}" # restore positional parameters
echo "FILE EXTENSION = ${EXTENSION}"
echo "SEARCH PATH = ${SEARCHPATH}"
echo "LIBRARY PATH = ${LIBPATH}"
echo "DEFAULT = ${DEFAULT}"
echo "Number files in SEARCH PATH with EXTENSION:" $(ls -1 "${SEARCHPATH}"/*."${EXTENSION}" | wc -l)
if [[ -n $1 ]]; then
echo "Last line of file specified as non-opt/last argument:"
tail -1 "$1"
fi
EOF
chmod +x /tmp/demo-space-separated.sh
/tmp/demo-space-separated.sh -e conf -s /etc -l /usr/lib /etc/hosts
Output from copy-pasting the block above
FILE EXTENSION = conf
SEARCH PATH = /etc
LIBRARY PATH = /usr/lib
DEFAULT =
Number files in SEARCH PATH with EXTENSION: 14
Last line of file specified as non-opt/last argument:
#93.184.216.34 example.com
Usage
demo-space-separated.sh -e conf -s /etc -l /usr/lib /etc/hosts
Bash Equals-Separated (e.g., --option=argument)
cat >/tmp/demo-equals-separated.sh <<'EOF'
#!/bin/bash
for i in "$@"; do
case $i in
-e=*|--extension=*)
EXTENSION="${i#*=}"
shift # past argument=value
;;
-s=*|--searchpath=*)
SEARCHPATH="${i#*=}"
shift # past argument=value
;;
-l=*|--lib=*)
LIBPATH="${i#*=}"
shift # past argument=value
;;
--default)
DEFAULT=YES
shift # past argument with no value
;;
*)
# unknown option
;;
esac
done
echo "FILE EXTENSION = ${EXTENSION}"
echo "SEARCH PATH = ${SEARCHPATH}"
echo "LIBRARY PATH = ${LIBPATH}"
echo "DEFAULT = ${DEFAULT}"
echo "Number files in SEARCH PATH with EXTENSION:" $(ls -1 "${SEARCHPATH}"/*."${EXTENSION}" | wc -l)
if [[ -n $1 ]]; then
echo "Last line of file specified as non-opt/last argument:"
tail -1 $1
fi
EOF
chmod +x /tmp/demo-equals-separated.sh
/tmp/demo-equals-separated.sh -e=conf -s=/etc -l=/usr/lib /etc/hosts
Output from copy-pasting the block above
FILE EXTENSION = conf
SEARCH PATH = /etc
LIBRARY PATH = /usr/lib
DEFAULT =
Number files in SEARCH PATH with EXTENSION: 14
Last line of file specified as non-opt/last argument:
#93.184.216.34 example.com
Usage
demo-equals-separated.sh -e=conf -s=/etc -l=/usr/lib /etc/hosts
To better understand ${i#*=} search for "Substring Removal" in this guide. It is functionally equivalent to `sed 's/[^=]*=//' <<< "$i"` which calls a needless subprocess or `echo "$i" | sed 's/[^=]*=//'` which calls two needless subprocesses.
Using bash with getopt[s]
getopt(1) limitations (older, relatively-recent getopt versions):
- can't handle arguments that are empty strings
- can't handle arguments with embedded whitespace
More recent getopt versions don't have these limitations. For more information, see these docs.
POSIX getopts
Additionally, the POSIX shell and others offer getopts which doen't have these limitations. I've included a simplistic getopts example.
cat >/tmp/demo-getopts.sh <<'EOF'
#!/bin/sh
# A POSIX variable
OPTIND=1 # Reset in case getopts has been used previously in the shell.
# Initialize our own variables:
output_file=""
verbose=0
while getopts "h?vf:" opt; do
case "$opt" in
h|\?)
show_help
exit 0
;;
v) verbose=1
;;
f) output_file=$OPTARG
;;
esac
done
shift $((OPTIND-1))
[ "${1:-}" = "--" ] && shift
echo "verbose=$verbose, output_file='$output_file', Leftovers: $@"
EOF
chmod +x /tmp/demo-getopts.sh
/tmp/demo-getopts.sh -vf /etc/hosts foo bar
Output from copy-pasting the block above
verbose=1, output_file='/etc/hosts', Leftovers: foo bar
Usage
demo-getopts.sh -vf /etc/hosts foo bar
The advantages of getopts are:
- It's more portable, and will work in other shells like
dash.
- It can handle multiple single options like
-vf filename in the typical Unix way, automatically.
The disadvantage of getopts is that it can only handle short options (-h, not --help) without additional code.
There is a getopts tutorial which explains what all of the syntax and variables mean. In bash, there is also help getopts, which might be informative.
The simplest and most widely available method to get user input at a shell prompt is the read command. The best way to illustrate its use is a simple demonstration:
while true; do
read -p "Do you wish to install this program?" yn
case $yn in
[Yy]* ) make install; break;;
[Nn]* ) exit;;
* ) echo "Please answer yes or no.";;
esac
done
Another method, pointed out by Steven Huwig, is Bash's select command. Here is the same example using select:
echo "Do you wish to install this program?"
select yn in "Yes" "No"; do
case $yn in
Yes ) make install; break;;
No ) exit;;
esac
done
With select you don't need to sanitize the input – it displays the available choices, and you type a number corresponding to your choice. It also loops automatically, so there's no need for a while true loop to retry if they give invalid input.
Also, Léa Gris demonstrated a way to make the request language agnostic in her answer. Adapting my first example to better serve multiple languages might look like this:
set -- $(locale LC_MESSAGES)
yesptrn="$1"; noptrn="$2"; yesword="$3"; noword="$4"
while true; do
read -p "Install (${yesword} / ${noword})? " yn
if [[ "$yn" =~ $yesexpr ]]; then make install; exit; fi
if [[ "$yn" =~ $noexpr ]]; then exit; fi
echo "Answer ${yesword} / ${noword}."
done
Obviously other communication strings remain untranslated here (Install, Answer) which would need to be addressed in a more fully completed translation, but even a partial translation would be helpful in many cases.
Finally, please check out the excellent answer by F. Hauri.
Best Answer
This will get you count:
You can work with the result as with object:
And if you would like to have aliases in some variable also, you can use Tee-Object:
Some more info on Measure-Object cmdlet is on Technet.
Do not confuse it with Measure-Command cmdlet which is for time measuring. (again on Technet)