In Bash script, how to join multiple lines from a file? For example, to join the lines a good boy to a good boy You can use tr command, something like: tr -s ‘n’ ‘ ‘ < file.txt It just goes through its input and makes changes according to what you specify in two sets
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Tag: Command line
How to save the output of screen windows to a file on Linux?
Posted onIn the screen, copying the history of the window output is quite hard. How to save the screen easily to a file? First type Ctrl + A then : to get to command mode. In the command mode, execute hardcopy -h /path/to/file screen will save the window output to /path/to/file.
How to handle spaces in paths with rsync on Linux?
Posted onThe common rsync commands seems not handle spaces well. For example, rsync -avxP file “user@server:/data/my dir” It reports: rsync: link_stat “/home/zma/file” failed: No such file or directory (2) How to make rsync handle spaces well? You can use the –protect-args option of rsync. $ rsync –protect-args -avxP file “user@server:/data/my dir” What does –protect-args do: -s,
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How to install sshfs on CentOS 7?
Posted onsshfs is a nice tool. But it seems there is no support to it in a newly installed CentOS 7 Linux system: Not installed by default: # sshfs -bash: sshfs: command not found Seems not available from the repositories # yum install sshfs -y Loaded plugins: fastestmirror Repodata is over 2 weeks old. Install yum-cron?
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How to install PARSEC correctly.
Posted onPARSEC is the most important CPU-bound benchmark for systems. It is huge and hard to install because it needs lots of 3-part libs. PARSEC download link for 3.0 version: http://parsec.cs.princeton.edu/download.htm#parsec I remembered I added the answer yesterday night but I could not see the answer currently. Anyway, let me add the answer again after I
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How to grep a tab on Linux?
Posted onHow to grep a tab on Linux? Including ‘t’ seems not working. grep can grep tabs. The problem is likely the tab is not passed to grep. If you are using Bash, you can use ANSI-C quoting to pass the “tab” to grep: $ grep $’t’ file.txt Or, use Perl-style regex (only for GNU grep)
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How to choose the key used by SSH for a specific host?
Posted onHow to choose a key used rather than the default ~/.ssh/id_rsa when ssh to a remote server for a specific host? You have at least 2 choices for choosing the key used by ssh. Taking ~/.ssh/key1 and user@example.com as the example here. Method one, specify the key in command line with the -i option of
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How to check whether a function has been defined in Bash?
Posted onI would like to know whether a function, say f1(), has already been defined in Bash. How should I do it? You can use the type -t to get a string of the type of the name: If the -t option is used, type prints a string which is one of alias, keyword, function, builtin,
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How to disable an option with a bash script?
Posted onIt is possible to set an option inside a Bash script such as set -o errexit. But how to do the reverse thing, that is, to unset an option? Change – to + to do the reverse thing of unseting an option in bash. For example, to unset the errexit option set by set -o
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How to get the metadata of an AWS S3 object?
Posted onI upload files using the aws cli http://www.systutorials.com/239665/uploading-large-files-amazon-s3-aws-cli/ . But how to get the metadata of an object in AWS S3? You can use the s3api‘s head-object command to get the metadata of an object. Taking one example: $ aws s3api head-object –bucket test-hkust –key dir2/fileupload/fb0c6353-a90c-4522-9355-7cd16cf756ff.file.txt It will print results like { “AcceptRanges”: “bytes”, “ContentType”:
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How to get the CPU temperatur in command linux on Linux?
Posted onMost modern servers or computers have sensors to detect the temperature of various components. On Linux, how to get the CPU core temperatur in command linux? First, make sure the package “lm-sensors” is installed on your Linux and the command sensors works for you. Then, you can use this piece of script to get the
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How to change a user’s username on Linux?
Posted onI want to rename a user’s username on Linux. For example, rename user u1 to user1. How to change a user’s username on Linux? You can use the usermod command to modify the user’s info. For changing the user name, you can use the -l option: -l, –login NEW_LOGIN The name of the user will
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How to test whether PATH has a specific directory in it in Bash on Linux?
Posted onHow to test whether PATH has a specific directory in it in Bash on Linux? For example, how to test whether /usr/local/mytool/bin is in $PATH? Directories in the $PATH variable are separated by :. So you can use a regular expression to test whether the $PATH contains a directory. The code for your specific example
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How to make the rpcbind.service auto start in systemd on Linux?
Posted onThe command systemctl enable rpcbind.service seems not work. The rpcbind.service does not start after rebooting. How to make/force the rpcbind.service auto start in systemd on Linux? You an force the rpcbind.service to start by making it be “wanted” by the target such as multi-user: # systemctl add-wants multi-user rpcbind.service This will force rpcbind.service to start.
How to test a file or directory exists in Python?
Posted onIn Bash, the [ -f ] and [ -d ] tests can test whether a file or a directory exist. What are the corresponding python method for these tests? For -f: **os.path.isfile(path)** Return True if path is an existing regular file. This follows symbolic links. For -d: **os.path.isdir(path)** Return True if path is an existing
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How to get another user’s PATH in Bash on Linux?
Posted onHow to get the $PATH environment variables of another user in Bash on Linux? The current user running the Bash script is root. If the scripts is run by root, this piece of code will store the PATH from the environment of the user user1: user1path=$(su – $user1 -c env | grep ^PATH= | cut
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How to scp multiple files from remote to local on Linux?
Posted onWith scp, copying several files such as file1 file2 to remote site can be passed by command line like $ scp file1 file2 user@remote: But how to scp multiple files from remote to local on Linux? You can do similar things by at least 2 method with scp: $ scp user@remote:file{1,2} ./ $ scp user@remote:”file1
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How to config Git remote server on Bitbucket or Github
Posted onFor your first push with git, you may get following errors when you use github or bitbucket. $ git push No refs in common and none specified; doing nothing. Perhaps you should specify a branch such as ‘master’. fatal: The remote end hung up unexpectedly Everything up-to-date Just run following command to set your remote
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How to test whether a user already exist on Linux?
Posted onHow to test whether a user account, say linuxuser, already exist on Linux? You may make use of id which tries to get user IDs. The Bash code snippet is as follows. user=hello id -u $user >/dev/null 2>&1 if [ “$?” == “0” ]; then echo “user $user already exist.” else echo “user $user doesn’t
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How to move cursor to a specific byte in Vim?
Posted onIn Vim, ’20G’ moves the cursor to line 20 in command mode. But how to move the cursor to a specific byte in Vim? In normal mode, 20go will move the cursor to byte 20. Or in command line, :goto 20 or :go 20 From vimdoc: :[range]go[to] [count] [count]go Go to {count} byte in the
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