Visit Our UNIX and Linux User Community


what does " ||" mean? ( Double pipe)


 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting what does " ||" mean? ( Double pipe)
# 1  
Old 08-30-2007
Lightbulb what does " ||" mean? ( Double pipe)

I found a line in one of the shell scripts,

cd /tmp || exit 2


What does this double pipe "||" mean?

Can any one tell what it is doing?


Thanks in advance.
# 2  
Old 08-30-2007
if the first command succeed the second will never be executed
Or
if the cd /tmp fails it will execute 'exit 2'
# 3  
Old 08-30-2007
If the exit status of the first command (cd /tmp) is not 0, then execute the second command (exit 2).
It's the opposite of '&&', where the second command is executed only if the exit status of the preceding command is 0.

For example:

Code:
$ ls this_file_does_not_exist.txt || echo KO
ls: cannot access this_file_does_not_exist.txt: No such file or directory
KO

$ ls this_file_exist.txt && echo OK
this_file_exist.txt
OK

# 4  
Old 09-12-2007
Thery are both correct but i believe that you are looking for this:

the || in a script "shell or perl" refers to: OR.

|| is equal to OR

So all your scripts are saying do this || \ OR this

Previous Thread | Next Thread
Test Your Knowledge in Computers #678
Difficulty: Medium
Wi-Fi positioning systems use the positions of local cellular towers to identify the location of a Wi-Fi device.
True or False?

9 More Discussions You Might Find Interesting

1. AIX

Apache 2.4 directory cannot display "Last modified" "Size" "Description"

Hi 2 all, i have had AIX 7.2 :/# /usr/IBMAHS/bin/apachectl -v Server version: Apache/2.4.12 (Unix) Server built: May 25 2015 04:58:27 :/#:/# /usr/IBMAHS/bin/apachectl -M Loaded Modules: core_module (static) so_module (static) http_module (static) mpm_worker_module (static) ... (3 Replies)
Discussion started by: penchev
3 Replies

2. Shell Programming and Scripting

Bash script - Print an ascii file using specific font "Latin Modern Mono 12" "regular" "9"

Hello. System : opensuse leap 42.3 I have a bash script that build a text file. I would like the last command doing : print_cmd -o page-left=43 -o page-right=22 -o page-top=28 -o page-bottom=43 -o font=LatinModernMono12:regular:9 some_file.txt where : print_cmd ::= some printing... (1 Reply)
Discussion started by: jcdole
1 Replies

3. UNIX for Dummies Questions & Answers

Using "mailx" command to read "to" and "cc" email addreses from input file

How to use "mailx" command to do e-mail reading the input file containing email address, where column 1 has name and column 2 containing “To” e-mail address and column 3 contains “cc” e-mail address to include with same email. Sample input file, email.txt Below is an sample code where... (2 Replies)
Discussion started by: asjaiswal
2 Replies

4. Shell Programming and Scripting

The pipe not use "tee" to print on the screen for specific function

I have code fragment like { aa bb cc } > $LOG aa bb cc, all call function "ff", I want "ff" to print on the screen,but others do not print on the scree, is there a method? I can't use "tee", becasue tee I meet the write "error" ff() { echo "hello" } (2 Replies)
Discussion started by: yanglei_fage
2 Replies

5. Shell Programming and Scripting

How to allign output data in UNIX that is separated with a pipe "|" symbol ?

Experts , In the given output of the log file, the 2nd field that is separated by "|" pipe is not aligned well due to the uneven data length, I would like it to align the 2nd column with 37 length (that is disturbed in the output) including the pipe . The two pepe "|" would be in a aligned way... (2 Replies)
Discussion started by: rveri
2 Replies

6. Shell Programming and Scripting

awk command to replace ";" with "|" and ""|" at diferent places in line of file

Hi, I have line in input file as below: 3G_CENTRAL;INDONESIA_(M)_TELKOMSEL;SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL My expected output for line in the file must be : "1-Radon1-cMOC_deg"|"LDIndex"|"3G_CENTRAL|INDONESIA_(M)_TELKOMSEL"|LAST|"SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL" Can someone... (7 Replies)
Discussion started by: shis100
7 Replies

7. Programming

fork&pipe "interpretting" shell - problem

hello everybode.Got some sort of "problems" with this stuff; well this is a program int main() { int Pipe; int origStdin, origStdout; int childPID; origStdin = dup(0); origStdout = dup(1); pipe(Pipe); if( (childPID = fork()) < 0 ) { perror(... (2 Replies)
Discussion started by: IdleProc
2 Replies

8. UNIX for Dummies Questions & Answers

Encoding Problem while using "|" (PIPE) as delimiter from Mainframe to Unix

We are facing a problem with PIPE (|) as a delimiter in one of our FTP flat files. We are constructing a Flat file in IBM-AIX and this contains various strings delimted by PIPE Symbol and then FTPing this to a Mainframe System The Mainframe program simply recieves this and FTPs the same... (1 Reply)
Discussion started by: seshendra
1 Replies

9. UNIX for Dummies Questions & Answers

Explain the line "mn_code=`env|grep "..mn"|awk -F"=" '{print $2}'`"

Hi Friends, Can any of you explain me about the below line of code? mn_code=`env|grep "..mn"|awk -F"=" '{print $2}'` Im not able to understand, what exactly it is doing :confused: Any help would be useful for me. Lokesha (4 Replies)
Discussion started by: Lokesha
4 Replies

Featured Tech Videos