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I'm working on a bash script that will search for a specific file using wildcard path to search, once it finds that filename it searches inside the file for a specific term and then replaces it.

Here's what i've put together already:

#!/bin/sh

PATH=${1}
FILENAME="$2"
SEARCHFOR="$3"

/usr/bin/clear
echo "Searching $PATH"
echo "For the file $FILENAME"
echo "With the string $SEARCHFOR"
echo "=========================="
echo "       RESULTS            "
echo "=========================="
/usr/bin/find $PATH -type f -name "$FILENAME" | /usr/bin/xargs /bin/grep -l "$SEARCHFOR"

I haven't added the replacement yet but I figured i would use SED instead of grep to do that, just using grep for testing purposes.

With the code above i have to use quotes for any type of wildcard paths. Is there a way around this?

./script '/home/*/public_html' php.ini module.so

I was thinking maybe using arguments but there's got to be another way to do it.

My ultimate goal is to have a bash script i can pass a wildcard path or filename to, it will search for that file, once it finds the file it searches for a specific term and replaces it if found.

Sounds so simple and it should be but i'm banging my head against the desk because it's been so long since i've messed with bash...aaggghh help!

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  • Just a side note, defining $PATH overrides the PATH variable defined by your shell which tells it what folders to look in when running a command. For example, when you type python myscript.py the shell searches the semicolon-separated directories in $PATH for an executable named python and uses that -- it eliminates the need to type /usr/bin/python myscript.py. By overwriting it, you'll likely break the parts of the script that follow your definition. TLDR: You should really consider using a different name for your variable. Commented Sep 7, 2012 at 2:04
  • As a follow up, this is why you have to write /usr/bin/clear instead of just clear and the reasoning behind William Pursell's answer. Commented Sep 7, 2012 at 2:07

5 Answers 5

Reset to default
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First of all, its a bad, bad, really bad idea to have variable names declared in upper case, especially PATH since you would be actually re-setting the actual PATH environment variable (just do a echo $PATH in the prompt and you will understand what I mean, and this is probably one of the reasons why you had to use /usr/bin/clear instead of clear since the env variable PATH gets modified). So, its always recommended to use variables with lower case like path.

The problem you are facing is with glob expansion of * within the subshell. When you use 

./script '/home/*/public_html' php.ini module.so

the * is not expanded at the prompt (parent shell) but is expanded inside the script's subshell. But when you use

./script /home/*/public_html php.ini module.so

the * is expanded in the parent shell (which would result in one random path as pointed to by the shell) and then gets passed inside the program subshell-

So lets say, /home has directories /user, /apps,/data doing $ cd * would take you to the directory which is alphabetically first i.e. /apps. So /home/* without quotes in the parent shell will always point to /home/apps which is not what we want!

An immediate remedy to this is as below

$set -o noglob   #unset glob expansion
$./script /home/*/public_html php.ini module.so    #your command without quotes & wildcard */
$set +o noglob   #re-set glob expansion back

or

$set -o noglob;./script /home/*/public_html php.ini module.so;set +o noglob

Try $echo * and then $set -o noglob;echo *;set +o noglob for a quick example.

Caveat- if you fail or forget to set noglob back (set +o noglob), the shell will treat characters like * and ? like normal characters and will not expand them which might lead to undesirable results and confusion.

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1 Comment

+1 nice call on setting PATH + having to call /usr/bin/... for everything following
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find $path -name \*$filenamepattern\* -exec sed -i.bak 's/find/replace/g' {} ';'
  • sed -i will do find and replace inside the file and save back to the file
  • remove .bak part if you don't want to backup the files
  • leverage -exec option of find to avoid slightly more cumbersome xargs
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1 Comment

I am not sure how this answer is relevant to the question. The OP wants to run ./script '/home/*/public_html' php.ini module.so without the quotes around the path and is wondering why the command does not work without the quotes.
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Just reorder your arguments and put the list of directories you want to search at the end. So:

#!/bin/sh

FILENAME="${1?No filename specified}"
SEARCHFOR="${2?No target string given}"
shift; shift;
SEARCHPATH="$@"

Then you should be able to leave the rest unchanged (other than changing the name PATH to SEARCHPATH, since changing the PATH is a really bad idea) and call it as:

$ ./script php.ini module.so /home/*/public_html
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4 Comments

+1 not only because of the downvote (shame on the voter; you should leave a comment indicating what's wrong). This is the correct solution, in accordance to broadly respected Unix conventions and just because it's simple and not astonishing.
But wouldn't * get expanded before its passed to the Subshell (i.e. to the program)? The purpose is to have * expand inside the programs subshell, but here the * would get expanded in the parent shell itself if its not surrounded by quotes! (FYI- I was not the down voter though) @william pursell
@Annjawn yes, the * will be expanded before being passed to the script. But "$@" is the expanded value, which is then passed on to find.
Oh i got it now... You were using $@.
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find `filepath` -name `filename`|xargs sed 's/find/replace/'

for me I would use find and sed to finish the work.

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1 Comment

Backticks? Why would you use backticks around filepath and filename. Also, there is no $ in these and they look like variables (and they are absolutely not a shell command).
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This will solve the problem of passing wildcards to a bash script BUT please obey the first bullet point.

#!/bin/bash -f

directory=$1
filename=$2
searchfor=$3
replacement=$4

sedpattern=s/$searchfor/$replacement/g

find $directory -name $filename -exec sed -i.bak $sedpattern {} ';'
  • IMPORTANT when invoking this script on the command line, you must backslash-escape your globs;
    • % ./thisscript . \*.csv oldword newword
  • bash -f option turns off globbing at the right time - when bash subshell is first invoked, meaning before parameters are parsed;
  • find command execs sed on all files that match
  • easiest way to pass a search-replace pattern to sed that contains other defined variables inside a script is to place the pattern itself in a variable first
  • -i.bak option creates a new file with the replacements, as well as backup up the original file
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