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UNIX for Advanced & Expert Users
[Discussion] POSIX, the Love of Backticks and All That Jazz
Post 302990666 by Scrutinizer on Monday 30th of January 2017 12:13:13 PM
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9 More Discussions You Might Find Interesting
1. Shell Programming and Scripting
Can someone explain the difference between backticks and system when
evaluated in these if statements:
sub getDate {
print "start date\n";
if ( system("/bin/date") ) {
print "can't get date\n";
exit(2);
}
print "finish date\n";
}
Returns the following:
start date
Thu... (5 Replies)
Discussion started by: gjkeenan
5 Replies
2. Shell Programming and Scripting
Hi, I'm trying to do something like this: range= `expr `date '+%m'` - 1` and it does not work. How can I tell it to evaluate an expression within another expression evaluation? I was at first worried that `date '+%m'` would return a string but apparently expr does the math okay normally, so the... (3 Replies)
Discussion started by: jeriryan87
3 Replies
3. UNIX for Dummies Questions & Answers
Hi,
I would like to change some lines in my mysql-dump, because there a syntax problems with some version of mysql.
I 'd like to change
USE ´someDatabase´;
to
USE someDatabase;
(without backticks) using the sed command in the shell
Thanks & best regards
Bernd (5 Replies)
Discussion started by: bjb
5 Replies
4. Shell Programming and Scripting
I'm always concerned I might be abusing backticks within my scripts. A current script I'm writing has this for example:
stripscriptname=`echo $scriptname | sed 's/\(.*\)\..*/\1/'`
stripsearch=`echo $searchpattern | tr -d ' ,/'`
Both of these variables are set inside the script (in fact,... (2 Replies)
Discussion started by: mglenney
2 Replies
5. Shell Programming and Scripting
Hey all. Just a fast question, what is the technical difference between using back ticks and using xargs to perform a command?
Here's an example
Find /mydir -name *.conf |xargs rm
Vs
Rm 'find /mydir -name *.conf'
Is there a performance hit? I know they do the same thing but which is... (1 Reply)
Discussion started by: msarro
1 Replies
6. Red Hat
Hi everyone. This is a bit of a perl/linux mixed question. I am trying to redirect STDOUT of chsh by using the following line of perl code.
system ("chsh -s /sbin/nologin $testing 1>/dev/null");
This should redirect STDOUT to /dev/null but it won't do that for some odd reason. Any ideas or... (6 Replies)
Discussion started by: austinharris43
6 Replies
7. Shell Programming and Scripting
Input file:
'data_1'
'data_10'
'data1311'
'235data_13'
Desired output:
data_1
data_10
data1311
235data_13
Can I know how to remove back tick"'" in a file?
Many thanks for advice. (3 Replies)
Discussion started by: perl_beginner
3 Replies
8. Shell Programming and Scripting
I have been testing a new script and cannot figure out why my `cat spath` will not execute on the remote machine?
sudo ssh -p 22344 -o "PasswordAuthentication no" -o "HostbasedAuthentication yes" -l testuser 192.168.1.6 "find `cat spath` -depth"
cat: spath: No such file or directory
but... (0 Replies)
Discussion started by: metallica1973
0 Replies
9. Shell Programming and Scripting
I'm trying to make a dialog window that prints the output of grep that takes the output of find. Unfortunately my nested backticks don't work.
Here is the dialog window:
dialog --stdout --title "test" --backtitle "test" --msgbox "Test:\n `grep -l "${tablica}" `find $string``" 16 60I think I... (2 Replies)
Discussion started by: Starting_Leaf
2 Replies
LEARN ABOUT HPUX
sh
sh(1) General Commands Manual sh(1) NAME
sh - overview of various system shells SYNOPSIS
POSIX Shell option] ... string] [arg ...] option] ... string] [arg ...] Korn Shell option] ... string] [arg ...] option] ... string] [arg ...] C Shell [command_file] [argument_list ...] Key Shell DESCRIPTION
Remarks The POSIX .2 standard requires that, on a POSIX-compliant system, executing the command activates the POSIX shell (located in file on HP-UX systems), and executing the command produces an on-line manual entry that displays the syntax of the POSIX shell command-line. However, the command has historically been associated with the conventional Bourne shell, which could confuse some users. To meet stan- dards requirements and also clarify the relationships of the various shells and where they reside on the system, this entry provides com- mand-line syntax and a brief description of each shell, and lists the names of the manual entries where each shell is described in greater detail. The Bourne shell is removed from the system starting with HP-UX 11i Version 1.5. Please use the POSIX shell as an alternative. Shell Descriptions The HP-UX operating system supports the following shells: POSIX-conforming command programming language and command interpreter residing in file Can execute commands read from a terminal or a file. This shell conforms to current POSIX standards in effect at the time the HP-UX system release was introduced, and is similar to the Korn shell in many respects. Similar in many respects to the Korn shell, the POSIX shell contains a history mechanism, supports job control, and provides various other useful features. Korn-shell command programming language and commands interpreter residing in file Can execute commands read from a terminal or a file. This shell, like the POSIX shell, contains a his- tory mechanism, supports job control, and provides various other useful features. A command language interpreter that incorporates a command history buffer, C-language-like syntax, and job control facilities. Restricted version of the POSIX shell command interpreter. Sets up a login name and execution environment whose capabilities are more controlled (restricted) than normal user shells. restricted version of the Korn-shell command interpreter Sets up a login name and execution environment whose capabilities are more controlled (restricted) than normal user shells. An extension of the standard Korn Shell that uses hierarchical softkey menus and context-sensitive help. +--------------+--------------------+ | To obtain: | Use the command: | +--------------+--------------------+ | POSIX Shell | /usr/bin/sh ... | | Korn Shell | /usr/bin/ksh ... | | C Shell | /usr/bin/csh ... | | Key Shell | /usr/bin/keysh | +--------------+--------------------+ These shells can also be the default invocation, depending on the entry in the file. See also chsh(1). WARNINGS
Many manual entries contain descriptions of shell behavior or describe program or application behavior similar to ``the shell'' with a ref- erence to ``see sh(1)''. SEE ALSO
For more information on the various individual shells, see: keysh(1) Key Shell description. ksh(1) Korn Shell description. sh-posix(1) POSIX Shell description. csh(1) C Shell description. sh(1)