I have a script that calls find internally and id like to do something like this:
FIND_CRITERIA="-name \"*.[ch]\" -o -name \"*.cpp\" -o -name \"*.hpp\""
if [ "$1" != "" ]; then
FIND_CRITERIA=$1
fi
echo "Find command: find / ${FIND_CRITERIA} > /tmp/output.txt"
find / ${FIND_CRITERIA} > /tmp/output.txt
It prints exactly the find command I'd like to execute. However it doesn't execute it correctly.
Does anyone knows why?
Thanks very much.
Short answer: see BashFAQ #50:I'm trying to put a command in a variable, but the complex cases always fail!.
Long answer: when the shell parses a command like find / ${CRITERIA}, it first parses quotes, escapes, etc; then it replaced variables like ${CRITERIA} with their values, but does not go back through them to look for quotes etc -- it's already done that. As a result, putting quotes, escapes, etc in variables doesn't do anything useful.
The best way to do this sort of thing in bash is to store the parameters in an array:
#!/bin/bash
CRITERIA=(-name "*.[ch]" -o -name "*.cpp" -o -name "*.hpp")
echo "Find command: find / ${CRITERIA} > /tmp/output.txt"
find / "${CRITERIA[@]}" > /tmp/output.txt
...but this won't work with the way you're treating $1 as an optional set of criteria. Does the script need any other arguments? If not, I'd recommend having it take the search criteria as separate arguments rather than a single one (i.e. ./findscript -name "*.c" instead of ./findscript "-name \"*.c\""), like this:
#!/bin/bash
if [ $# -gt 0 ]; then
CRITERIA=("$@")
else
CRITERIA=(-name "*.[ch]" -o -name "*.cpp" -o -name "*.hpp")
fi
echo "Find command: find / ${CRITERIA} > /tmp/output.txt"
find / "${CRITERIA[@]}" > /tmp/output.txt
EDIT: Based on your comment about needing to allow other options/arguments to the script, I see three options:
Use eval to parse the getopt argument into an array:
case "$opt" in
f) eval "CRITERIA=($OPTARG)" ;;
This has all of the usual problems associated with eval, mainly having to do with failing in weird (and possibly dangerous) ways depending on what's passed as the OPTARG. Ick.
If the script doesn't need to take any "regular" (non-option) arguments, pass the criteria as regular arguments (./script -a -b -c -d -- -name ".cpp" -o -name ".hpp"). The problem with this is that IIRC Correction: at least in bash version 3.2.48, getopts doesn't read -- as a delimiter between options and regular arguments, so you'd have to do at least some of the parsing "by hand".getopts handles -- automatically.
If the only criteria you need to pass are -name's, you can use multiple -f options to specify name patterns to build the criteria, e.g. ./script -a -b -c -d -f "*.cpp" -f "*.hpp"
CRITERIA=()
...
case "$opt" in
f) if [[ ${#CRITERIA[@]} -eq 0 ]]; then
CRITERIA=(-name "$OPTARG")
else
CRITERIA+=(-o -name "$OPTARG")
fi ;;
...
if [[ ${#CRITERIA[@]} -eq 0 ]]; then
CRITERIA=(-name "*.[ch]" -o -name "*.cpp" -o -name "*.hpp")
fi
a with a[${#a}]="new value"; there maybe a shorthand way to do it (but it isn't a+="new value"; that adds the new value to the zeroth element of the array).a+="new value" is wrong for an array, but a+=("new value") with the parentheses is correct.You are calling $CRITERIA whereas the variable name is $FIND_CRITERIA . I assume that's a typo.
Try this instead :
#!/bin/bash
FIND_CRITERIA="-name \"*.\[ch\]\" -o -name \"*.cpp\" -o -name \"*.hpp\""
if [ "$1" != "" ]; then
FIND_CRITERIA=$1
fi
echo "Find command: find / ${FIND_CRITERIA} > /tmp/output.txt"
echo "${FIND_CRITERIA}" | xargs find / > /tmp/output.txt
FIND_CRITERIAandCRITERIAin your example. Typo?