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Three small Linux commands can solve everyday terminal problems without a script: shuf randomizes lines or picks a sample, timeout puts a time limit on a command, and tee saves output while letting it continue through a pipeline. These examples describe GNU Coreutils behavior; availability and details can vary with your distribution, installed package, and version.
1. Use shuf to mix lines or pick a sample
shuf outputs a random permutation of input lines. Add -n to limit how many lines it prints:
shuf -n 3 names.txtThis prints three randomly selected lines from names.txt. It is handy for a casual choice or a quick sample from a list. GNU Coreutils 9.11 also accepts explicit values with -e and can generate a range with -i:
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shuf -i 1-10To choose five values from a short list while allowing repeats, use replacement mode, -r:
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shuf -r -n 5 -e red blue greenWithout -r, the output is a permutation of the supplied values, so a value will not appear more times than it appears in the input. These are ordinary randomization conveniences, not a basis for security decisions or a cryptographic lottery. See the GNU Coreutils 9.11 shuf documentation.
2. Use timeout to bound a command’s run time
Put a duration before a command to have GNU timeout signal it when that interval expires:
timeout 10s some-commandGNU Coreutils 9.10 uses TERM by default. A timeout normally returns status 124; scripts can use that status to distinguish a timeout from many other outcomes. The command’s actual stopping time can depend on system conditions and how it responds to the signal, so this is not a guarantee of instantaneous cleanup.
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3. Use tee to save output as it flows
tee copies standard input both to standard output and to one or more files. This lets you watch a command’s output while saving it:
make 2>&1 | tee build.logHere, 2>&1 sends standard error to the same place as standard output before the pipe, so both streams reach tee. The output remains visible in the terminal and is written to build.log. By default, an existing file with that name is overwritten. Add -a to append instead:
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make 2>&1 | tee -a build.logOne scripting detail: in some shells, a pipeline’s reported status reflects only its last command, which can hide a failure from the command before tee. In Bash, enable pipefail when you want the pipeline to report an earlier failure:
set -o pipefail
make 2>&1 | tee build.logThat behavior belongs to the shell’s pipeline status rules, not to tee. See the GNU Coreutils 9.11 tee documentation.
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shuf: shuffle input lines or take a limited random sample.timeout: give a command a time limit and signal it when the limit expires.tee: save a stream to a file while forwarding it onward or to the terminal.
For short command examples to keep nearby, tldr-pages offers community-maintained practical summaries alongside fuller references such as manual pages.
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