Bash – Why 2 linux machine behave differently with command of the same syntax

bashfindshellwildcards

I am using 2 machine , which is both Red Hat Enterprise Linux AS release 3 (Taroon Update 2)
( I check it in /etc/*-release ).

I checked they are using the same default shell by ps -p $$, which is bash.

I tried to execute a find command with wildcard pattern:
find path -name pattern -type f -ctime +3

and the pattern contain * character as wildcard.

The first machine seems to expanded the wildcard character and causing error:

find /home/primbat/testing -name sftp_bcs_report_*.log -type f -ctime +7
find: paths must precede expression

and I need to either make the pattern in between 2 delimited qoute, e.g: \"sftp_bcs_report_*.log\" or using set -f in the script to suppress wildcard expansion.

Which in the other machine, it have no such problem. Do you have any idea?

Best Answer

By default, shells expand wildcards if a file matches them but keep unexpanded without match. For example, if you run touch /tmp/111; touch /tmp/11* this will create and then update mtime on /tmp/111, but if /tmp is empty but you call touch /tmp/11* you will get file named "11*" in /tmp.

This is rather weird feature of shells. Sometimes proper expanding isn't possible without special hacks as intermediate function. Most current shells invent special options for typical cases; e.g. "shopt -s failglob" in bash rejects it from running any command where wildcard match fails.

One shall rely on find's wildcard expanding, so such pattern shall be quoted against expansion in shell:

find /home/primbat/testing -name 'sftp_bcs_report_*.log' -type f -ctime +7

(note single quotes). With zero or one file, it works, but with two or more files you get broken command syntax and it complains - this is what is said by colleague Arcege. Your "set -f" disables expansion totally - well, it is good measure for diagnostics but can give underwater rakes for a future moving. Quotes are simpler:)

Related Solutions

Bash – How to programmatically tell if a filename matches a shell glob pattern

I don't believe that {bar,baz} is a shell glob pattern (though certainly /foo/ba[rz] is) but if you want to know if $string matches $pattern you can do:

case "$string" in 
($pattern) put your successful execution statement here;;
(*)        this is where your failure case should be   ;;
esac

You can do as many as you like:

case "$string" in
($pattern1) do something;;
($pattern2) do differently;;
(*)         still no match;;
esac

PuTTY – Pasting Text with Tabs into a Here-Document

When you type into a shell, the shell recognizes some characters as commands. For example, the carriage return character (the character sent by the Enter key) causes the shell to execute the command. The tab character causes the shell to perform completion. When you paste something into the PuTTY terminal window, from the shell's point of view, that's the same thing as if you'd typed these characters. So at the point the tab character is pasted, the shell performs completion, it doesn't insert a tab.

The easiest way to copy a file without it being transformed would be to use PuTTY's companion program PSCP or PSFTP to copy the file. This is the simplest way conceptually, but it does have the overhead of running another program, authenticating, choosing a directory, etc.

If you want something inline, you can paste directly into cat, rather than in a here document. Then you'd be pasting into the terminal's line editor, not into the shell's line editor. As the terminal's line editor is very primitive, only a few control characters have a special meaning there, not including tab. Press Ctrl+D at the beginning of a line to terminate the input.

[darkstar /]$ cat >text.txt
Paste
Ctrl+D
[darkstar /]$

I you want to transfer arbitrary data over a medium that interprets control characters, you can encode it into a form that uses only “tame” characters. Base64 is one; it doesn't use any control character and ignores whitespace and newlines. GNU coreutils, which is part of the basic installation on Linux and Cygwin, includes a base64 command. On the sender side, run base64 <file-to-decode, e.g.

On Windows: run base64 c:/path/to/test.txt from a Cygwin terminal
Copy the output.
In the shell in the PuTTY window, type `base64 -d >/tmp/test.txt and press Enter.
Paste the output from base64.
Press Ctrl+D.

Best Answer

Related Solutions

Bash – How to programmatically tell if a filename matches a shell glob pattern

PuTTY – Pasting Text with Tabs into a Here-Document

Related Question