Actually this is a pipeline consisting of two components (mysqldump and gzip). The success of this pipeline depends in the success of the two programs; either mysqldump may fail or gzip (or both ofcourse). It's better to rewrite these lines as follows:
The pipefail bash option is controlling the exit status of a pipeline (read the manual pages for bash). Of course the two components must be written correctly from their authors (exiting with non zero exit statuses when failures occur).
Hi friends, :)
In a shell script i found the following if condition.
echo -n "Which version of $1 do you want to restore ('0' to quit)? : "
read desired
if ${desired:=1} -ge $index ] ; then
echo "$0: Restore canceled by user: index value too big." >&2
exit 1
fi
Can... (1 Reply)
i have a paramter data_date in which i am passing a string value.i want to find out another paramter file_date from this.the logic is given below
if day of data_date = sunday or monday
then
file_date=data_date-1
else
file_date=data_date-2
i am passing data_date as 20061027.
how can i... (3 Replies)
Hi,
I am trying to execute this command, but is it not working, says "`;' unexpected"
eval $lgrep $SAM_CMD ; if ; then ; echo "No Error" ; fi
What i want is, return the command output, if it is non zero, say "No Error".
Thanks, John. (21 Replies)
Executed the following if conditions .. and got different results .
only (( )) gave correct o/p with all scenarios .
Can anybody please let me know what is the difference between and ] and ((condition)) when used with if condition.
And why each condition gave different result.
1.... (2 Replies)
hi,
I have some problems in my simple script about the redirect echo stdout command inside a condition. Why is the echo command inside the elif still execute in the else command
Here are my simple script
After check on the two diff output the echo stdout redirect is present in two diff... (3 Replies)
HI
My doubt may be basic one but I need to get it clarified..
When i use "if" condition that checks for many AND, OR logical conditions
like
if ]; then
return 0
fi
Even the if condition fails it returns as zero.. Any clue..
But if i add else condition like
if ]; ... (2 Replies)
Hi all
Unix newbie - please be gentle
Am modifying an existing script to error trap a variable with a length of 0
#!/bin/bash
ipfile='/var/data/bin/ipaddress'
] && ipold="$(< "$ipfile" )"
ipnew="$( wget -q -O - checkip.dyndns.org | sed -e 's/.*Current IP Address: //;s/<.*$//' )"
#... (6 Replies)
o/p of my command is given below
My requirement is
if Pnumber is 0 then
stabilization.Build.2013
else
stabilization.PBuild.2013.3 (11 Replies)
Discussion started by: nikhil jain
11 Replies
LEARN ABOUT CENTOS
which
WHICH(1) General Commands Manual WHICH(1)NAME
which - shows the full path of (shell) commands.
SYNOPSIS
which [options] [--] programname [...]
DESCRIPTION
Which takes one or more arguments. For each of its arguments it prints to stdout the full path of the executables that would have been exe-
cuted when this argument had been entered at the shell prompt. It does this by searching for an executable or script in the directories
listed in the environment variable PATH using the same algorithm as bash(1).
This man page is generated from the file which.texinfo.
OPTIONS --all, -a
Print all matching executables in PATH, not just the first.
--read-alias, -i
Read aliases from stdin, reporting matching ones on stdout. This is useful in combination with using an alias for which itself. For
example
alias which='alias | which -i'.
--skip-alias
Ignore option `--read-alias', if any. This is useful to explicity search for normal binaries, while using the `--read-alias' option in
an alias or function for which.
--read-functions
Read shell function definitions from stdin, reporting matching ones on stdout. This is useful in combination with using a shell func-
tion for which itself. For example:
which() { declare -f | which --read-functions $@ }
export -f which
--skip-functions
Ignore option `--read-functions', if any. This is useful to explicity search for normal binaries, while using the `--read-functions'
option in an alias or function for which.
--skip-dot
Skip directories in PATH that start with a dot.
--skip-tilde
Skip directories in PATH that start with a tilde and executables which reside in the HOME directory.
--show-dot
If a directory in PATH starts with a dot and a matching executable was found for that path, then print "./programname" rather than the
full path.
--show-tilde
Output a tilde when a directory matches the HOME directory. This option is ignored when which is invoked as root.
--tty-only
Stop processing options on the right if not on tty.
--version,-v,-V
Print version information on standard output then exit successfully.
--help
Print usage information on standard output then exit successfully.
RETURN VALUE
Which returns the number of failed arguments, or -1 when no `programname' was given.
EXAMPLE
The recommended way to use this utility is by adding an alias (C shell) or shell function (Bourne shell) for which like the following:
[ba]sh:
which ()
{
(alias; declare -f) | /usr/bin/which --tty-only --read-alias --read-functions --show-tilde --show-dot $@
}
export -f which
[t]csh:
alias which 'alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'
This will print the readable ~/ and ./ when starting which from your prompt, while still printing the full path when used from a script:
> which q2
~/bin/q2
> echo `which q2`
/home/carlo/bin/q2
BUGS
The HOME directory is determined by looking for the HOME environment variable, which aborts when this variable doesn't exist. Which will
consider two equivalent directories to be different when one of them contains a path with a symbolic link.
AUTHOR
Carlo Wood <carlo@gnu.org>
SEE ALSO bash(1)WHICH(1)