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Standard Error Redirect Ksh

do I redirect error messages? Note: The following information pertains primarily to Bourne-like shells, such as sh, ksh, and ksh redirect output to file bash. To redirect standard error messages to a file, enter: command ksh redirect stderr and stdout to /dev/null 2> file Replace command with the command you want to execute and file with the file to

Ksh Redirect Stderr To Dev Null

which you want to direct the errors, for example: gunzip * 2> ~/errors If you wish to suppress error messages, enter: command 2>&- If you wish to redirect

Ksh Redirect Output To File And Screen

error messages to standard output, enter: command 2>&1 You can direct both standard error and standard out messages to an output file by entering the following: command > file 2>&1 The csh and tcsh shells have substantially less flexible redirection capabilities. However, from sh or tcsh you can invoke a Bourne-like shell to run a command ksh tee that redirects standard error messages. To redirect standard error messages, enter the following: ksh -c 'commands' You can use sh or bash in the place of ksh. Replace commands with redirection syntax, for example: ksh -c 'ls -l foo 2> ~/notfound' At Indiana University, for personal or departmental Linux or Unix systems support, see At IU, how do I get support for Linux or Unix? Related documents Introduction to Unix commands In Unix, where can I get information on differences between the various shells? This is document agvw in the Knowledge Base. Last modified on 2008-08-22 00:00:00. I need help with a computing problem Fill out this form to submit your issue to the UITS Support Center. Please note that you must be affiliated with Indiana University to receive support. All fields are required. Full name Email address Please provide your IU email address. If you currently have a problem receiving email at your IU account, enter an alternate email address. Relationship to Indiana University --Sel

ls | wc -l But bourne-shell derivatives give you even more power than that. Most properly written programs output in one of two ways. Progress messages go to stdout, error messages go to stderr Data goes to stdout, error

Ksh Exec Redirect

AND progress messsages go to stderr If you know which of the categories your utilities fall ksh pipe into, you can do interesting things. Redirection An uncommon program to use for this example is the "fuser" program under solaris. it gives ksh else if you a long listing of what processes are using a particular file. For example: $ fuser /bin/sh /bin/sh: 13067tm 21262tm If you wanted to see just the processes using that file, you might initially groan and wonder how best https://kb.iu.edu/d/agvw to parse it with awk or something. However, fuser actually splits up the data for you already. It puts the stuff you may not care about on stderr, and the meaty 'data' on stdout. So if you throw away stderr, with the '2>' special redirect, you get $ fuser /bin/sh 2>/dev/null 13067 21262 which is then trivially usable. Unfortunately, not all programs are that straightforward :-) However, it is good to be aware of these things, and http://www.bolthole.com/solaris/ksh-redirection.html also of status returns. The 'grep' command actually returns a status based on whether it found a line. The status of the last command is stored in the '$?' variable. So if all you care about is, "is 'biggles' in /etc/hosts?" you can do the following: grep biggles /etc/hosts >/dev/null if [[ $? -eq 0 ]] ; then echo YES else echo NO fi As usual, there are lots of other ways to accomplish this task, even using the same 'grep' command. However, this method has the advantage that it does not waste OS cycles with a temp file, nor does it waste memory with a potentially very long variable. (If you were looking for something that could potentially match hundreds of lines, then var=`grep something /file/name` could get very long) Inline redirection You have seen redirection TO a file. But you can also redirect input, from a file. For programs that can take data in stdin, this is useful. The 'wc' can take a filename as an argument, or use stdin. So all the following are roughly equivalent in result, although internally, different things happen: wc -l /etc/hosts wc -l < /etc/hosts cat /etc/hosts | wc -l Additionally, if there are a some fixed lines you want to use, and you do not want to bother making a temporary file, you can pretend part of your script is a

Variables Action on Success or Failure of a Command Trivial Calculations Numerical Calculations using "bc" "grep" "sed" "awk" "perl" Principle of Script Defining the Shell Type To make a ksh script (which is a ksh program) crate a new file with a starting line like: #!/usr/bin/ksh It http://www.well.ox.ac.uk/~johnb/comp/unix/ksh.html is important that the path to the ksh is propper and that the line doesn http://superuser.com/questions/195560/re-redirect-stderr-in-k-sh not have more than 32 characters. The shell from which you are starting the script will find this line and and hand the whole script over to to ksh. Without this line the script would be interpreted by the same typ of shell as the one, from which it was started. But since the syntax is different for all shells, it ksh redirect is necessary to define the shell with that line. Four Types of Lines A script has four types of lines: The shell defining line at the top, empty lines, commentary lines starting with a # and command lines. See the following top of a script as an example for these types of lines: #!/usr/bin/ksh # Commentary...... file=/path/file if [[ $file = $1 ]];then command fi Start and End of Script The script starts at the first line ksh redirect output and ends either when it encounters an "exit" or the last line. All "#" lines are ignored. Start and End of Command A command starts with the first word on a line or if it's the second command on a line with the first word after a";'. A command ends either at the end of the line or whith a ";". So one can put several commands onto one line: print -n "Name: "; read name; print "" One can continue commands over more than one line with a "\" immediately followed by a newline sign which is made be the return key: grep filename | sort -u | awk '{print $4}' | \ uniq -c >> /longpath/file Name and Permissions of Script File The script mus not have a name which is identical to a unix command: So the script must NOT be called "test"! After saveing the file give it the execute permissions with: chmod 700 filename. Variables Filling in When filling into a variable then one uses just it's name: state="US" and no blanks. There is no difference between strings and numbers: price=50. Using When using a variable one needs to put a $ sign in front of it: print $state $price. Arrays Set and use an array like: arrname[1]=4To fill in print ${arraname[1]}To print out ${arrname[*]}Get all elements ${#arrname[*]}Get the number of eleme

here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Super User Questions Tags Users Badges Unanswered Ask Question _ Super User is a question and answer site for computer enthusiasts and power users. Join them; it only takes a minute: Sign up Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top Re-redirect STDERR in K/SH? up vote 1 down vote favorite Once STDERR is redirected, for example to a file, how can it be redirected back to the original file descriptor 2? #!/bin/sh exec 2>/tmp/err print -u2 'log errors to file' exec 2>&2 (how do we do this???) print -u2 'log errors to console' Context This redirection solution should work in a cron job. For example, if cron executes an external script, that script will redirect stdout and stderr to relevant log and error files, respectively. However, if an execution in the script fails or something needs to be reported to the job owner, I need to output the error messages so cron will receive them and send mail. shell shell-script ksh share|improve this question edited Oct 4 '10 at 7:07 asked Oct 4 '10 at 5:34 Clint Pachl 79858 add a comment| 1 Answer 1 active oldest votes up vote 2 down vote accepted Try: #!/usr/bin/env ksh exec 2>ksh_err.txt print -u2 'log errors to file' exec 2>`tty` print -u2 'log errors to console' Edit 1: #!/usr/bin/env ksh exec 8>err.txt print -u8 'log errors to file' print -u2 'log errors to console' Edit 2: #!/usr/bin/env ksh exec 3>&2 exec 2>err.txt print -u2 'log errors to file' exec 2>&3 print -u2 'log errors to console' share|improve this answer edited Oct 4 '10 at 10:05 answered Oct 4 '10 at 6:49 Casual Coder 2,7431712 This would work if my situation was different. I just updated my question. –Clint Pachl Oct 4 '10 at 7:08 I've updated my answer. –Casual Coder Oct 4 '10 at 8:20 That would work too, but just not in my case because I cannot control which file descriptor gets written to. The script in question running from cron contains dump(8). Dump by default writes status/progress to STDERR and dump data to STDOUT (pipe to SSH). I want to redirect dump's STDERR to a dumplog for the entire script because there are several invocations of dump throughout the script. However, if the script must report other errors, I would like to do a re-redirect back to the original STDERR on file descriptor 2. Hope that makes sense. –Clint Pachl Oct 4

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unix ksh error redirection
Unix Ksh Error Redirection p do I redirect error messages Note The following information pertains primarily to Bourne-like shells such as sh ksh and bash To redirect standard error messages to a file ksh redirect stderr and stdout to file enter command file Replace command with the command you want to execute p Ksh Redirect Stderr To File p and file with the file to which you want to direct the errors for example gunzip errors p Ksh Redirect Output To File p If you wish to suppress error messages enter command - If you wish to redirect error messages