1
vote
2answers
45 views

Call background process back to stdout

Is it possible to "call" a background process output to be shown in the terminal? Example: cron starts apt-get to update the system and I want to see the output of apt-get
2
votes
4answers
76 views

Command line 'buffer' [duplicate]

I wanted to tail the last 100 lines of a file to the same file, but the command tail -n 100 file > file doesn't work, I assume because the stdout gets written to the file 'live', before everything ...
4
votes
2answers
89 views

How to redirect stdout to a file and read from the same file simultaneously with another task?

I want to run a task (which takes quite a long time) remotely in Ubuntu Linux Bash via nohup and redirect stdout to a file, e.g.: nohup task > out.txt & From time to time I would like to ...
1
vote
3answers
86 views

Inserting the command line text before output in stdout (for pipe / redirection)

Consider the following bash constructs: ls /usr/include/asm > list-redir.txt ls /usr/include/asm | tee list-tee.txt In this case, list-redir.txt and list-tee.txt will be identical, and will ...
4
votes
4answers
143 views

How do I break up a file like split to stdout for piping to a command?

I have a large .sql file full of SELECT statements that contain data I want to insert into my SQL Server database. I'm looking for how I could basically take the file's contents, 100 lines at a time, ...
4
votes
1answer
154 views

Piping commands, modify stdin write to stdout

echo Hello World | nano - | less I want to modify Hello -> Goodbye while in the the text editor. It does not have to be with nano. I am stuck with nano reading stdin but requiring me to write to a ...
4
votes
3answers
471 views

Dynamically trim stdout line width in Bash

Lately, I have been experimenting with the ps command, and sometimes long paths wrap to the next line (or two) and make it hard to read. I want to pipe the ps output into another program to limit the ...
2
votes
3answers
96 views

Is it possible to generate a separate file list when creating a tarball?

When using tar for backups I'd like to create a separate list of the files that is included in the archive for storing alongside the backup tarball. I also want to be able to store the error messages ...
1
vote
2answers
2k views

In bash script, how to capture stdout line by line

In a bash script, I would like to capture the standard output of a long command line by line, so that they can be analysed and reported while initial command is still running. This is the complicated ...
7
votes
2answers
275 views

Kill a process if it goes quiet for a certain amount of time

I have a utility that has a nasty habit of going quiet and staying there, I already know how long into the process it does this so I am using timeout to fight this, but sometimes it does it before ...
3
votes
2answers
205 views

Bash if script is called from terminal echo stdout to terminal, if from cron do not echo output

I would like to have a service watchdog script echo the status to the screen if called like ./watchdog.sh but if it is run by cron, there is no need to echo output. What is the proper method? Where ...
3
votes
5answers
901 views

How to use filename arguments or default to stdin, stdout (brief)

I want to handle filenames as arguments in a bash script in a cleaner, more flexible way, taking 0, 1, or 2 arguments for input and output filenames. when args = 0, read from stdin, write to stdout ...
10
votes
2answers
931 views

Script to quickly test all keyboard keys

I need to check some notebooks for bad keyboard keys, and so I'd like to speed that up as much as possible. I found nothing for this specific task, so my idea is a script that reads the pressed keys ...
1
vote
2answers
154 views

Turning standard output hyphen into a single command

I am working with scripts that output xml and I am using xmllint to format the output. Xmllint requires a source argument, so I use the hyphen to pipe standard output to it: $> script.php ...
2
votes
2answers
3k views

How to redirect error to a file?

I have this simple script which redirects the output and append it to a file. filename="/home/ronnie/tmp/hello" date=$(date) echo "$date" >> $filename Now, lets suppose I change date=$(date) ...
3
votes
2answers
3k views

Merge two command results to one line when redirecting stdout

In a cron script I want to log CPU temperatures in the format [datetime] temp using date and acpi -t. How can I redirect (>>) these two commands to a single line in the log file?
13
votes
2answers
726 views

Redirect stderr from an already running script

I've been running a script for several days now. I redirected stdout to $HOME/mylog, but didn't redirect stderr since I thought there would be nothing on it. Suddenly thousands of lines started coming ...
5
votes
1answer
788 views

Append output to a file and redirect stderr to null

How can I append the result of a command to a file and redirect stderr to null?
23
votes
4answers
4k views

How to do nothing forever in an elegant way?

I have a program which produces useful information on stdout but also reads from stdin. I want to redirect its standard output to a file without providing anything on standard input. So far, so good: ...
5
votes
2answers
599 views

Wrapping a shell script with tee

There is a bash script which prints some logs and allows some arguments. The script prints the logs to STDOUT. Let's say the script's name is AAA.sh I'd also like to make the script to print the logs ...
5
votes
3answers
5k views

bash: /dev/stderr: Permission denied

After upgrading to a new release version, my bash scripts start spitting errors: bash: /dev/stderr: Permission denied in previous versions Bash would internally recognize those file names (which is ...
4
votes
2answers
800 views

Can I read and write to the same file in Linux without overwriting it? [duplicate]

Possible Duplicate: How can I make iconv replace the input file with the converted output? I frequently connect to amazon ec2 using their public DNS names ...
1
vote
1answer
306 views

selective stdout , stderr and logging using the script command [duplicate]

Possible Duplicate: Show only stderr on screen but write both stdout and stderr to file stdout , stderr and logging using the script command cat test.sh: rm -v foo.tmp date pwd cat ...
1
vote
4answers
5k views

Can I access Nth line number of standard output?

Assuming a script that outputs a list of files: $> bash someScript.sh path/to/some/file path/to/the/file/i/want/to/work/with path/to/yet/another/file Now I want to have the second file-path as ...
8
votes
3answers
6k views

bash: Use a variable to store stderr|stdout redirection

Is there any way to redirect stdout and stderr via variable like adding command options in script? For example I have a script: #!/bin/bash -x TEST=">/dev/null 2>&1" OPT='-p -v' mkdir $OPT ...
2
votes
4answers
3k views

How to limit the number of lines a command's output has available in bash?

I started downloading a big file in the background using $ nohup wget http://example.tld/big.iso & which also gives me a nohup.out file that includes the output of wget. Now, if I later want ...