Sponsored Content
Full Discussion: Peculiar behavior due to IFS
Operating Systems Linux Peculiar behavior due to IFS Post 302775491 by RudiC on Tuesday 5th of March 2013 01:36:02 AM
Old 03-05-2013
Quote:
Originally Posted by alister
Quote:
Originally Posted by RudiC Image
Does it? I don't think so. The | char opens a pipe and makes the shell wait for the next command in the pipe.
The shell command parsing step which looks for pipes has already concluded by the time parameter expansion occurs. There's nothing special about a pipe character in a variable. You'd have to use eval to make it so.
The command that was given in post#1 was
Code:
aa=|
echo $aa

Executing this on the two systems I have at hand (Linux, FreeBSD) issues the secondary prompt (asking for the next command in pipe, I assume). The variable aa is not assigned to, it is not even defined afterwards. So I think my statement holds.
Of course, assigning an escaped | is totally different and absolutely OK.
 

10 More Discussions You Might Find Interesting

1. Linux

SUSE9.1 Peculiar Gigabit Lan performance.

I'm having some peculiar performance issues with my Gigabit Lan. I have some 100Mb devices so I can't do the necessary "jumbo Frame" tweaks for absolute optimum performance as I'd prevent them access. I'm getting appauling transfer rates sending files to the linux machine, around 10 Mbps 3%... (0 Replies)
Discussion started by: Mark Ward
0 Replies

2. Shell Programming and Scripting

a peculiar error with sftp

Whenever I sftped a particular gzipped file to a particular directory and then try to unzip it, I get Permission Denied error. With this file even I cannot do chmod. though the file permissions are -rw-r--r-- When same file I sftp to a different location I am able to gunzip it. Directory... (0 Replies)
Discussion started by: RishiPahuja
0 Replies

3. UNIX for Dummies Questions & Answers

the IFS variable

Hi all, Ok os heres my situation. I have created a database style program that stores a persons info (name,address,phone number etc.) in a file ("database"). after i read in all the values above, i assign them to a line variable: line="$name^$address^$phonenum" >> phonebuk as you can see... (1 Reply)
Discussion started by: djt0506
1 Replies

4. Shell Programming and Scripting

problem with IFS

hi, :) I set IFS=":" But when i try to echo $IFS,i am not getting any thing on the screen escept a blank line. any help pls. cheers RRK (11 Replies)
Discussion started by: ravi raj kumar
11 Replies

5. UNIX for Dummies Questions & Answers

Help on IFS command!

Hi! I am working in korn shell. I want to reset the dimiliter for the set command to "|" but instead of a command prompt return I am getting something as below After issuing the command I am getting this....as if the shell is expecting something else. Can anybody suggest what's the problem. ... (2 Replies)
Discussion started by: udiptya
2 Replies

6. Shell Programming and Scripting

regarding IFS=

hi i am a learner can some explain "export IFS=$(echo "\n\t\a")" i am not able to understand the functionality please help thanks Satya (1 Reply)
Discussion started by: Satyak
1 Replies

7. AIX

Peculiar permission problem

Scenario: Step 1. I'm logging into AIX server using user id called user1 Step 2. I'm traversing to home directory of user2 Note: This user2's home directory has the permissions drwxr-s--- Step 3. I'm issuing command pwd there. I'm getting the expected output. Step 4. I'm issuing the... (3 Replies)
Discussion started by: krishmaths
3 Replies

8. Shell Programming and Scripting

Nested ifs

hi I keep getting an error with this nested if statement and am getting the error unexpected end of file, can anyone help me as to why this wont execute? #!/bin/bash #script to check wether the -i -v statements run correctly removeFile () { mv $1 $HOME/deleted }... (3 Replies)
Discussion started by: somersetdan
3 Replies

9. Shell Programming and Scripting

Bash IFS

I am using bash and resetting IFS as below when reading the command line arguments. I do this so I can call my script as in Ex1. Ex1: ./synt2d-ray3dmod.bash --xsrc=12/20/30 This allows me to split both sides so that when I do "shift" I can get 12/20/30 What I do not understand is... (21 Replies)
Discussion started by: kristinu
21 Replies

10. Shell Programming and Scripting

Not able to understand IFS

Hi , i am in my initial learning phase of unix. i was going thru the function part. below is the example which was there but i am not able to understand logic and the use of IFS(internal field separator) lspath() { OLDIFS="$IFS" IFS=: for DIR in $PATH ; do echo $DIR ; done IFS="$OLDIFS"... (8 Replies)
Discussion started by: scriptor
8 Replies
filter_create_fd(3)						   util/filter.h					       filter_create_fd(3)

NAME
filter_create_fd - Create a sub process and return the requested pipes SYNOPSIS
#include <util/filter.h> NEOERR *filter_create_fd(const char *cmd, int *fdin, int *fdout, int *fderr, pid_t *pid); ARGUMENTS
cmd -> the sub command to execute. Will be executed with /bin/sh -c fdin -> pointer to return the stdin pipe, or NULL if you don't want the stdin pipe fdout -> pointer to return the stdout pipe, or NULL if you don't want the stdout pipe fderr -> pointer to return the stderr pipe, or NULL if you don't want the stderr pipe DESCRIPTION
filter_create_fd and filter_create_fp are what popen been: a mechanism to create sub processes and have pipes to all their input/output. The concept was taken from mutt, though python has something similar with popen3/popen4. You control which pipes the function returns by the fdin/fdout/fderr arguments. A NULL value means "don't create a pipe", a pointer to an int will cause the pipes to be created and the value of the file descriptor stored in the int. You will have to close(2) the file descriptors yourself. RETURN VALUE
fdin -> the stdin file descriptor of the sub process fdout -> the stdout file descriptor of the sub process fderr -> the stderr file descriptor of the sub process pid -> the pid of the sub process SEE ALSO
filter_wait(3), filter_create_fp(3), filter_create_fd ClearSilver 12 July 2007 filter_create_fd(3)
All times are GMT -4. The time now is 03:59 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy