PS: in quoting as a reference i use chap7 from "learning the bash shell 3rd edition" but i am relatively new to shell scripting.Is there any other good reference for bash?
The "man" pages are a good reference.
You're right, by the way -- the * doesn't get expanded inside double-quotes. However, it's the ctags_command assignment that would give you problems:
Here's another way to do it:
Yet another way is with xargs:
The xargs command takes the output from find, and runs the ctags command as many times as needed (not once for each file, but as many times as required if the command line cannot hold all the arguments on one line). The -a command ensures ctags appends to the existing tags file in case xargs does need more than one call.
Hi All
In a script, I want a user to enter 4 characters, these can be a mix of letters (uppercase and lowercase) and numbers.
In this example $var represents what the user has entered.
eg $var can be A9xZ, 3DDL, bbHp .........etc
I need to check that the user has only entered characters... (2 Replies)
Hi,
I have trouble with quotations of the M4 preprocessor.
I want to write a basic makro that removes all spaces and newlines at the end and at the beginning of a string.
I tried this:
define(`TRIM_END', `patsubst(`$1', `\(\\n\| \)*$', `')')
define(`TRIM', `patsubst(`TRIM_END(`$1')',... (0 Replies)
I'm trying to take the command `date` giving me:
Fri Feb 22 09:23:52 EST 2008
and using some command take out the rest of the string leaving me with
"Fri Feb 22"
any help appreciated hopefully thanks in advance (3 Replies)
The block below isn't a surprise:$ ls
file1 file2 file3
$ x=*
$ echo $x
file1 file2 file3
$ echo '$x'
$x
$ echo "$x"
*
$But I found this block a bit bewildering:$ echo $x'
>'
*
$I'm wondering why substitution wasn't performed on the $x, since it was unquoted (as far as I can tell).... (5 Replies)
I think this has to do with the quoting, I just feel I've been looking at it too long. Thanks ~T
prompt> cat my.awk
BEGIN{"date +%d%b%Y.%H%M%S" | getline sDate}
{
if (substr($0,151,1) ~ /6/ )
print >> sDate".NEW_ORDER.dat"
# print >> sDate # note this works to output the contents to sDate,... (2 Replies)
Hi all,
i have a file that looks like:
one:two:three:four:five
six:seven:eight:nine:ten
and i'd like to quote the fourth column, getting:
one:two:three:"four":five
six:seven:eight:"nine":ten
i was thinking something like:
awk 'BEGIN{FS=":"}{print $1 FS $2 FS $3 FS \"$4\" FS $5}'... (5 Replies)
Hi,
My first shell script is one that prints the five largest directories in a given directory. My current effort is as follows, it gives me the output I'd like, but I have to quote a globbed pathname, which seems wrong:
#!/bin/sh
du -hs $1 | sort -rn | head -n 5
And I must invoke... (2 Replies)
I have some data files that I can identify by a certain pattern in the names using find.
Every one of those data files has an XML file associated with it (can be multiple data files per XML file).
The XML file is always up one directory from the data file(s) in a folder calledRun##### -... (12 Replies)
I am trying to write a BASH script that will prompt a user to enter a number of days, then calculate the date.
My problem is the date command uses single or double quotes. For Example..
date -d "7 days"
Here is an example of some same code I am trying to work through.
echo "when do you... (4 Replies)
Discussion started by: javajockey
4 Replies
LEARN ABOUT CENTOS
shell-quote
SHELL-QUOTE(1) User Contributed Perl Documentation SHELL-QUOTE(1)NAME
shell-quote - quote arguments for safe use, unmodified in a shell command
SYNOPSIS
shell-quote [switch]... arg...
DESCRIPTION
shell-quote lets you pass arbitrary strings through the shell so that they won't be changed by the shell. This lets you process commands
or files with embedded white space or shell globbing characters safely. Here are a few examples.
EXAMPLES
ssh preserving args
When running a remote command with ssh, ssh doesn't preserve the separate arguments it receives. It just joins them with spaces and
passes them to "$SHELL -c". This doesn't work as intended:
ssh host touch 'hi there' # fails
It creates 2 files, hi and there. Instead, do this:
cmd=`shell-quote touch 'hi there'`
ssh host "$cmd"
This gives you just 1 file, hi there.
process find output
It's not ordinarily possible to process an arbitrary list of files output by find with a shell script. Anything you put in $IFS to
split up the output could legitimately be in a file's name. Here's how you can do it using shell-quote:
eval set -- `find -type f -print0 | xargs -0 shell-quote --`
debug shell scripts
shell-quote is better than echo for debugging shell scripts.
debug() {
[ -z "$debug" ] || shell-quote "debug:" "$@"
}
With echo you can't tell the difference between "debug 'foo bar'" and "debug foo bar", but with shell-quote you can.
save a command for later
shell-quote can be used to build up a shell command to run later. Say you want the user to be able to give you switches for a command
you're going to run. If you don't want the switches to be re-evaluated by the shell (which is usually a good idea, else there are
things the user can't pass through), you can do something like this:
user_switches=
while [ $# != 0 ]
do
case x$1 in
x--pass-through)
[ $# -gt 1 ] || die "need an argument for $1"
user_switches="$user_switches "`shell-quote -- "$2"`
shift;;
# process other switches
esac
shift
done
# later
eval "shell-quote some-command $user_switches my args"
OPTIONS --debug
Turn debugging on.
--help
Show the usage message and die.
--version
Show the version number and exit.
AVAILABILITY
The code is licensed under the GNU GPL. Check http://www.argon.org/~roderick/ or CPAN for updated versions.
AUTHOR
Roderick Schertler <roderick@argon.org>
perl v5.16.3 2010-06-11 SHELL-QUOTE(1)